Acid is a bright-green liquid material that dissolves anything tagged [corrosive], which includes basically everything but glass, dense rock, and extremely dense rock. Like Lava, acid inflicts contact damage instead of staining the player. When released, acid flows downward, corroding materials in its path and releasing Flammable Gas as it evaporates.
Touching acid inflicts between 20 and 500 damage per second, depending on how much of the entity is in contact with the material, and aside from Ambrosia and Stainless Armour, nothing prevents or reduces acid damage. Without a massive health pool, acid threatens instant death at all points of a run.
- Rarely, as the player's starting potion
- Uncommonly, as a pedestal or chest item
- As blood or attacks from certain enemies, such as the Happonuljaska and Äitinuljaska and their variants
- In giant glass vats in Snowy Depths and The Vault
- From destructible red rocket-shaped barrels
- Created by Acid (Spell), Circle of Acid, and other spells
Acid's extreme damage can end almost any run before the player can react, and once released, it will burrow through nearly anything. In any biome containing acid, the player should proactively take extreme caution to avoid it. Some suggestions include:
- Carefully crack acid vats, detonate drums, and smash flasks from a safe distance
- Desperately avoid losing the high ground to any enemy that spits or bleeds acid
- Use redundant triggers, delays, and cast-delay-increasing measures to cast acid spells from screens away
Because acid represents a sudden-death threat, it's too dangerous for utility or offensive uses. Cast acid spells and use acid potions only in the most dire do-or-die situations.
Be particularly wary about acid reaching the bottom of a biome. If enough Holy Mountain Brickwork is corroded, the gods will summon Stevari, regardless if the player, a monster, or dumb luck is responsible. If acid is in play, quickly move from portal to Full Health Restore, in case a Stevari appears and knocks you back before you can heal.