My usual method of farming here is to get all chests from floors 181-189 as you frequently get 3 Veil Potions in those chests but since it is still RNG it is up to you whether you do so or just aim for the Crystals. You can still get 5 Veil Potions on floors 191-199 but it's a LOT rarer so it's best to rush to the teleport stones from there. if you still have 5+ veil potions on floor 190 then there is a chance you can still make floor 200 but if it's -5 it's best to escape and restock VP and try again. On these floors, all weapons have the Exp Up Buff though I did not encounter any bow here so if that is what you want it's best you farm the chest at floors 161-181 (Which if I recall has a high chance of getting Veil Potions in floors 171-179 that is a lot better than 191-200's 191-199).

There might even be a Partner Weapon RNG which I will test later on my current floor which is 90.