Potions (!!!) - Make potion specific shops that prevent potions from pushing regular items out of the pool. Otherwise make potions only apper in potion slots in regular shops. Buff the fortitude potion and burn salve in any manner, and lower the max amount of potion slots to 4.
Monsters (!!!) - Add piety drain, conversion point drain and gold drain enemies to the game to prevent people from abusing mechanics that have been buffed/added since alpha days and have no counter ATM. If these preove good and challenging you could also ad monsters with revards in those areas, or add such rewards to already "over the curve monsters" such as AA's and Zombies.
Racial Buildings - Alow locker slots for really specific stuff that you don't want to see in shops, and make the quest's to unlock said stuff make them preps available from the racial building. Exclusive with guild preps, ofc.
Witch - Remove the Comicated I and II rewards from the game completely, and make the other ones significantly easier.
Razor Blade Smile - Add some more fodder to vicious Halls of Steel, and significantly lower the amount of death protections on the vicious Indomitable.
HALPMEH - make it not remove poison, and make increse it's cost to 4 mana. Alternatively/additionaly make it remove Poisonous and Lifesteal BOONS, to prevent monotheism abuse.
BYCEPSS - make it remove poison, add +1 DMG per lvl, and increse it's cost to 3 mana. It would still allow for GG piety farm, but not regen fighting at the same time, and you'd have to scum for it.
WONNAFYT - Make it impossible to hit slowed enemies, for a start, and lower it's cost.
GETINDARE - Have it stack dodge untill you dodge. You can still only cast it once before you attack, but the stacked dodge would remain untill you Dodge.
Orc - cap him off at some point, but reduce the overall monster health by a little bit possibly.
Halfling/Gnome - Increse conversion cost.
Monk - lower his starting resists and cap by any amount, and fine tune it along several updates.
Paladin - If HALMEH is nefed to cost 4 mana and not cure poison he would be significantly weakened. If you make HALPMEH remove TT poison BOON, as well as Drac's Lifesteal Boon, you would also deal with monotheism abuse.
Thief - Lower the effect of potions to 33% restore.
Conversion stone - make it unlockerable.
Reflex potions - Fix the tooltip to make it more understandable that you can in fact get 2 hits in. It was the biggest detractor from people "discovering" them earlier.
Agnostic's collar - Add some sort of limitation to it's use, keeping in mind that doing so would drasticaly increse dificulty of many vicious dungeons, and make a few impossible to comlete with a lot of classes.
Quest Reward / Elite items - lower the costs of item's that need unlocking, as cost/conversion ratio is more important than the effects of most items anyway.
Mysteria, EM, Jehora - if you buff burn salve, and fortitude enough, have these goods give out the potions as boons in some form or fashion. Adjust Jeohras HP and MP boons to one time, and add "converts a HP or MP potion into a STR or Schaden potion", respectively (I'd give the STR one to the mana boon, and the Schaden to the HP boon, think about it
GG - Increse the cost of Absolution, and definitely remove the poison/HALPMEH sinergy. You can move the cleansing effect to EM to make her more worthwhile, as GG has an abundance of quality boons. You can also move the healing boon to EM and adjust it in some way.
TT - Have tribute be payed 5 gold at a time, and boons give back 5 gold. Lower the potion boon to 25, but have it increse in cost, or redistribute the potions into two cheaper stacking boons again, but move Tiki's Edge to Binlor to give him a worthwhile ability.
Binlor - have his Piety giving boon give something other than piety - he's a piety farm. Possibly move the Tiki's Edge boon to him and make him a better alternative to Taurog for physical fighters. You can also add IMAWAL piety benefits to him.
Drac - Find some other penalty for Lifesteal - the 10% resist penalty is nowhere near worth the effect.