Here comes yet another application of the CP frenzy prepset: the fireball avalanche!
So take an elf wizard with Namtar's Ward + transmutation scroll + less glyphs, prep JJ, bearmace, shops scroll and more gold. For potions Schadenfraude, mana pot, and the anti debuff ones.
Before even doing your 1st kill, you just farm piety to increase your max mana, and also take a health boost. You can wait with converting stuff untill finding your altars, if you see GG, convert under him, otherwise stay with JJ.
When you transmute NW and convert your least useful glyph, you immediately gain 340 CP, and a handy 50 gold! With looting the shops, from 25 mana you can easily skyrocket all the way up to 40-45, and can also afford spell casting items.
Btw you won't even run out of blackspace. You can save about 20-25%, and be done with piety farming and popcorn bowling too.
Time to kill your 1st monster. On hard it's a lvl 4 (even if you could kill a 5, don't do it to avoid double dinging), on VT it's 3. Then just keep keep killing the highest stuff that dings you, but doesn't make you double ding. So you play like a mana based version of a health monster.
The great thing about it is that you save all your blackspace left, and remain with a massive popcorn bowl.
In hard you will never have a problem, and by lvl 5 you can spike weaker bosses without any sort of refills. The tougher ones go down to a single level catapult. If you wanted to do something super silly, you could play the entire dungeon pure caster style - with no refills and catapults.
Just to mention a lvl 10 wiz with 50 mana (common to reach with this strat), and a battlemage ring spikes for 610 damage, then for 700 if burning is kept.
For VT runs some planning and strategy is needed too. Even if you pile up that massive popcorn, that doesn't mean you will be able to consume it. Also pulling off the insta-ding kills will need some creativity: mixing in well timed hits (this is where the health boost pays out, and when activating Schadenfrauds), pisorfs or combining melee items with your caster set ( witchalok pendant, FH, whurgarbl etc.). Sometimes you will overkill the target by a few fireballs, in cases like this plan ahead and choose your next target, and gift him with your excess mana before doing the kill. Tricks like this can enable wonderful kills.
At times no matter what you do the ideal kill is unreachable. You could switch to a god who helps by a refill or boon, or kill something lower and eat popcorn, or use blackspace and kill something similar again.
During your harder bossfight it's recommended to chew on fatter popcorns between dings, this way you ultimately can squeeze out more levelups. For the same reason sometimes a portion of your mana is better spent on fireballing popcorn if you're just a few xp short of yet another ding.
This strat comes with a lot of counting since even burning plays a big role in kills, and you constantly have to keep an eye on bonus xp to save resources. To ease the latter I made an xp-table.http://s1.postimg.org/ul7f0xw5r/XP_table.png
A very good kill pattern is 3 - 5 - 7 - 9, then if possible the weaker boss, and now you're lvl 6, 1 xp short of a ding.
Even if you can't instakill your first boss, at level 5 you only need 3 xp for a level catapult.
Want to see some pics how effective this strat is?
From the 1st time I tried it, and was still experimental:http://s11.postimg.org/hcyq5e29v/spellslinger2.pnghttp://s27.postimg.org/jcbc1iflv/spellslinger6.png
After some refinement:http://s16.postimg.org/qzj4lwu1h/pyromaniac3.pnghttp://s12.postimg.org/ctwle74sd/pyromaniac5.png
And finally some VT tests:http://s2.postimg.org/6z6bnbz6h/practice7.pnghttp://s15.postimg.org/7iybo4ugb/VT_warmup2.pnghttp://s23.postimg.org/rkpckfwnv/slimy_wiz3.png
What I really like about this strat is that how reliable it is. On that VT Slime Pit run my lvl 9 monsters were awful - meatmen and gelatinous thing, many of my popcorns were meatmen too, my only real spellcasting item was blue orb,
I wasted a lot of piety by taking spirit pact and staying with JJ too long, and then I haven't even mentioned my big mistakes. Like autoconverting soul orb when my sub was the spider temple
In the end I still blasted SMM to crisps easily.