CYDSTEPP ("Side-step") is one of the Glyphs you can find in a game of Desktop Dungeons. When used, this Glyph grants you Protection from Killing Blow. Initially locked and available only to the Warlord, it can become unlocked and available for all classes.
CYDSTEPP is cast by simply clicking it.
When cast, CYDSTEPP will give your hero the ability "Protection from Killing Blow" (commonly referred to as "Protection from Death", "Death Protection" and so forth, although the concept is slightly different).
This ability will remain with the hero for an unlimited amount of time. However, it will instantly dissipate the moment your character receives a hit from a monster that would otherwise kill him. When this occurs, the hero's Health will be reduced to 1 instead of 0, and he will survive the hit. This is indicated by the words "Saved from Death" floating above your hero.
If the hero receives a hit that would not reduce him to 0 or less Health, the Protection effect does not trigger and does not dissipate. It is therefore possible to receive any number of hits from a monster without losing the Protection effect as long as the hero doesn't receive a Killing Blow.
CYDSTEPP will only protect you from attacks by enemies. Other effects that drop health below 0 or otherwise kill you (such as effects from racial abilities and/or Gods) will not trigger the protection, and will NOT save you from death.
CYDSTEPP is not cumulative: You may only be protected from one Killing Blow at a time. If your hero already has the "Protection from Killing Blow" ability, a second use of CYDSTEPP will not have any effect! However it is still considered a "successful" use of the Glyph, will cost Mana, and will trigger God-related effects if any. It does not matter which source gave you "Protection from Killing Blow", be it items, Gods, or a previous casting of CYDSTEPP.
Once a previous "Protection from Killing Blow" has dissipated due to a monster's attack, CYDSTEPP may be cast as normal.
A note to remember: Triggering a Death Gaze from a Gorgon or other monster is considered a Killing Blow, and will trigger the "Protection from Killing Blow" effect accordingly.
Any game played with the Warlord will start with the CYDSTEPP Glyph on the starting tile. The Warlord needs to pick it up if he intends to use it. CYDSTEPP always appears when playing the Warlord class, regardless of any other factors.
Once the Normal Dungeon is beaten with a Warlord, CYDSTEPP becomes fully unlocked. From that point onwards, the CYDSTEPP Glyph has a chance to appear in any dungeon played, regardless of any other factors. The chance for it to appear is supposedly the same as that of other Glyphs, though this has not yet been conclusively proven.
CYDSTEPP vs. Other Sources
CYDSTEPP is not the only source in the game for acquiring "Protection from Killing Blow". Items, Gods and Racial traits may bestow the same exact effect.
Remember that you can only be protected from one Killing Blow at a time. The only way to survive two Killing Blows in a row is to acquire the effect, use it up (by surviving a Killing Blow), and then acquire it again. You will need to repeat the process for every Killing Blow you wish to survive.
The source of the effect makes no difference!
CYDSTEPP is one of the few spells that has a serious impact on gameplay on its own - finding it in a Dungeon might dictate the rest of your game, if you choose to pick it up. This is especially true for all characters who subsist on heavy, powerful Melee combat - particularly Humans.
The general strategy involved is to cast CYDSTEPP as soon as you find it (or have the Mana for it), then replenish enough Mana to use it again (more than once, if at all possible) without actually activating it a second time. You then go fight a foe who is much tougher than you, to the point where it delivers a Killing Blow and your Protection leaves you alive at 1 Health. Proceed to cast CYDSTEPP a second time, and attack the monster again. You will remain at 1 Health, and will still be alive, after having delivered at least 2 blows to the enemy. If your Health was high enough to survive the first attack (or several), this will have increased the number of attacks you've made on the monster to 3 or more! You can continue surviving and casting CYDSTEPP over and over until you run out of Mana to cast it.
This strategy enables characters to take on very tough monsters in Melee combat. A character with a high Attack Strength can bring down monsters several level higher than himself this way.
The reason why this spell is usually used "stand-alone" like this is because it costs so much mana to use (10 for most characters), leaving little or no mana for other spells. However, it is always possible to give up the second step of the above strategy (casting the second CYDSTEPP and surviving another Killing Blow) and instead use the built-up mana for casting other spells, such as BURNDAYRAZ, APHEELSIK, etc. (see Spell Combos, below).
This is a simple and extremely effective two-punch combo. CYDSTEPP is used in the regular fashion to suffer as many Killing Blows as possible while inflicting a lot of damage on the monster. 5 Mana are kept "Aside" at the end of the CYDSTEPP volley to Poison the monster with APHEELSIK.
At that point you are free to explore for Mana and Health, cast CYDSTEPP again, refill Mana again if necessary, and repeat the process on the monster until it dies.
This combo can help you kill monsters that are of a MUCH higher level than yourself. The CYDSTEPP basically nullifies those monsters' Attack Strength (they'll just drop you to 1 Health every time, even if they have Death Gaze), and APHEELSIK makes sure that only the availability of unexplored tiles determines how much damage you can inflict on any monster.
This is the basic Melee-oriented equivalent of the BURNDAYRAZ+APHEELSIK combo.
Also remember that APHEELSIK doesn't work on the Undead, and can be Resisted by monsters who possess Magic Resistance.
For a Three-Glyph-Combo, try BLUDTOPOWA.
This is, usually, not a good combination of Glyphs to have. CYDSTEPP and BURNDAYRAZ are counterparts - they are the two primary Glyphs used to damage your enemies, where Melee-style characters employ the former, and spellcasters employ the latter. There is not much benefit in using the two together, especially when other combos can be acquired.
The main reason why it's usually one-or-the-other is that they both cost a large amount of Mana to use. BURNDAYRAZ works well in combination with cheaper spells, or alone. CYDSTEPP doesn't really leave Mana for anything other than cheaper spells, and is already excellent if you have the mana to cast it more than once!
However, barring other options, it is always possible to start your attack run with a BURNDAYRAZ fireball just to give your enemy the first "push". You will need no less than 16 Mana for that to work though, so again, this is not the most favourable solution.
At first this combination looks great: You can cast CYDSTEPP more often, and need to waste fewer tiles between fights. However, remember that characters who rely on CYDSTEPP will constantly be hanging around at 1 Health, so using this combo is risky.
If you have other means to get your Health back, such as lots of Potions, assistance from Gods or racial abilities, this combo is much more acceptable. In addition, this leaves one extra Glyph Slot to be used for a low-cost spell of your choice - preferably APHEELSIK. In a three-Glyph-combo, CYDSTEPP, BLUDTOPOWA and APHEELSIK can be devastating to your enemies!
These are two very simple and very common combos. The low casting cost of these two Glyphs means that either of them can be cast with the little extra Mana that always seems to hang around after casting CYDSTEPP.
Naturally, their use is very different: BYSSEPS should be cast between every blow, until you are left with just enough Mana to cast CYDSTEPP. If you can come by a little extra Maximum Mana, you can cast it for the first, second, and even third round of combat (if you can survive that long).
GETINDARE is a little different: It's a Mana saver combo. When you and your enemy reach the state where the next attack will kill both of you, instead of casting CYDSTEPP to survive this blow, cast GETINDARE. You will kill your enemy with the first strike, thus not wasting more than 3 Mana and not costing you any Health (though your Health would usually be 1 at this point...). Basically, it will save you about 7 Mana points per battle. This combo only works if you have enough Maximum Mana to cast both CYSTEPP and GETINDARE together (normally 13 Mana).
Choosing a Warlord for a dungeon will always spawn the CYDSTEPP Glyph on the starting tile (see above). Warlords rely on CYDSTEPP to kill high-level enemies by surviving their deadly blows while causing as much damage as possible to the monster. This is their primary method for taking out bosses, as well.
The same method is used by pretty much any other character who picks up CYDSTEPP once it's been unlocked, though each class will add its own twist to this method.
Note that the Warlord has a special benefit that other classes do not: When his Health is below 50% of Maximum, he receives a +30% Attack Bonus. And since the Warlord spends most of his time at 1 Health (after surviving Killing Blows), this bonus is applied very often. Note that the bonus is cumulative with all other attack bonuses, so you can even double this up with BYSSEPS (see above).
The Warlord may live on CYDSTEPP, but the Rogue is its greatest champion. Due to his extremely high attack damage, the Rogue can deliver massive damage to the enemy while sustaining several Killing Blows thanks to CYDSTEPP. In addition, the Rogue already has low health, and so doesn't sacrifice much from constantly hovering around 1 Health. Combine this with the Rogue's innate ability to First-Strike his victims, and you've got a winning combination - with two Glyph slots to spare!
Similarly to the Rogue, the Berserker is built on Attack Strength and can use CYDSTEPP to deliver a lot of damage to an enemy.
The downside to this is that to the Berserker, casting CYDSTEPP costs 12 Mana. Therefore finding and using CYDSTEPP early in the dungeon is rare. In addition, Berserkers tend to follow gods who dislike the use of CYDSTEPP, making this a little trickier choice.
Fighter, Thief, Assassin
All three are primarily Melee-oriented classes who can nonetheless withstand the cost of CYDSTEPP and benefit from it. If your character development is already leaning towards spellcasting though, you may want to forgo CYDSTEPP.
Another useful Melee class, the trick here is that you only need CYDSTEPP to lower your enemy's Health to the point where Death Gaze can finish it off. This saves up on some Mana, because on average you'll be using CYDSTEPP less often than other classes, especially if your Death Gaze ability is high.
While the Vampire has a strong Melee attack, he is completely incapable of using CYDSTEPP properly. This is because Health is the Vampire's chief commodity, and is always scarce. Dropping to 1 Health after surviving a Killing Blow means you cannot cast CYDSTEPP again - giving you only one Killing Blow survival per fight. This is much less preferable to the Vampire's supreme BURNDAYRAZ specialty.
CYDSTEPP and the Gods
Several Gods in the game have various opinions about the use of CYDSTEPP - they may favour it or reject it, depending on their own particular creeds.
As the god of Holy Warriors, Glowing Guardian respects any hero who can heroically risk his life and come out alive. For each use of the CYDSTEPP Glyph, he will reward you with +2 Piety Points. This occurs regardless of whether the character already had "Protection from Killing Blow" when the Glyph was cast.
To make things even better, for each time you actually survive a Killing Blow (I.E. trigger the effect of the spell), you will receive another Piety point. (Note that this happens regardless of whether the Protection effect came from CYDSTEPP or any other source).
This makes Glowing Guardian the veritable patron saint of CYDSTEPP.
The God of Chaos, Jehora prefers his combats messy and deadly. If you try to cheat death, you will be punished.
Jehora Jeheyu will deduct -10 Piety points each time you cast CYDSTEPP. Note that it doesn't matter if you already had the "Protection from Killing Blow" effect when you did so - you will still be punished.
Note, however, that the spell is still considered successful - it will cost Mana as normal, and will give you the "Protection from Killing Blow" effect!
As with any other Glyph, Taurog will penalize you -5 Piety points every time you use CYDSTEPP. Also, his reduction of Maximum Mana means you will usually remain with too little Mana to use the Glyph anyway.
When you rely on CYDSTEPP, worshipping Mystera is a big mistake. It may boost your Maximum Mana, allowing you to cast CYDSTEPP more often, but it also reduces your Attack Strength to 1 permanently, meaning that survival in Melee combat brings you virtually no benefit.