So Potions of Exchange now transmute a stack into up to 19 different items of the same type. The thing is, several ways are available in ADOM to make uniform stacks of potions again: assasin's lvl 6 class power, poisoned hands and artifacts containing essence of chaos and corruption (moon sickle being the best one)
This strategy is definitely scummy but seems legit to me. You need: gold and means to transform potions. Works MUCH better with potion belt, but also works without it.
1. Go to D:1 while being lawful. Be on your deity's good side for holy water in borderland settlement altar.
2. Buy everything from borderland settlement shop. It will give you lots of potions to experiment with. Treasure hunter also helps to accumulate more potions.
3. Put beauty-enhancing items on to reduce corrupting effects from dipping: diadem of beauty, pendant of beauty, (gorgeous) fine clothes, cloak of adornment, staff of beauty which may also be zapped. Bracers of pure might also help if you happen to find them.
4. Transmute all unneeded potions (i.e. everything except stat-raising, cure corruption, water, booze and exchange) into raw chaos (poison if you have potion belt, because dipping corrupted artifacts sometimes causes corruption). Poison weighs 4s and without belt can be transmuted in stacks of 4, PoRC weighs 2s and is dipped in stacks of 9. Potion belt negates weight and allows dipping and thus transmuting 19 potions per stack 4.Go to D:1 and dip for potions of exchange and occasionally gain attributes. Go to D:2 and 1/3 to 1/2 of a stack you are transforming will be potions of water.
5. Do not transmute potions of booze! Blessed booze has insane chance to get PoGA from Yggris the fool, about 1/10.
6. Most potions will be transmuted to uncursed ones, some to blessed and cursed. accumulate enough blessed/cursed potions for a full stack of cursed/blessed potions of raw chaos and you'll get most of potions as uncursed again. You may also bring some blessed scrolls of uncursing or uncursing spell to handle cursed potions.
Non-belt engine dies eventually because potions of exchange do not generate on every dip. Belt-enabled engine gives you relatively simple way to raise all attributes to 99, cure all corruption and get lots of disablers (potions of blindness/confusion). Of course it is not as powerful as pre-1.2 wishing engine but still powerful enough.
I tried to post it here earlier but my browser kept crashing so I've posted it on Reddit