You spray corrosive acid and microbial creatures that digest metal at the target.

Armor which provides resistance, immunity, or other specific protection from acid damage does not take armor damage from this spell (unless its element is changed).

The target takes 1d4 acid damage and 1 armor damage.
Intensify: +1d4 acid damage per boost from Intensify.

If the target is not already taking ongoing damage from your Corrode, it gets a health save.

Fail:
The target takes 1d4 ongoing acid damage and 1 ongoing armor damage at the start of each of its turns.
Intensify: +1d4 ongoing acid damage per boost from Intensify.
An affected creature may spend an action to get a health save against this spell’s DC to end all ongoing damage from this ability.
An affected creature may also remove their affected armor to stop taking ongoing damage from this ability (tossing a shield aside can be done instantly, but removing armor typically takes 1 minute).
Track your ongoing damage, and remind your headmaster about this damage at the start of each affected creature’s turn.

Pass:
The target does not take ongoing damage.

Armor Damage:
Each point of armor damage reduces armor or a shield’s AC bonus and physical damage reduction by 1.
This cannot reduce the AC bonus of that armor or shield below +0.
This cannot reduce physical damage reduction of that armor or shield below 0.
Indestructible gear cannot take armor damage.
Incorporeal targets cannot take armor damage.
(This does not work on spells such as Mage Armor, Stone Skin, Spirit Armor, Ward, etc.)
When used on a monster, armor damage can reduce it to 10 AC, not counting AC bonuses from spells or other abilities.

Damage Boosts:
Boosts to this spell’s damage add to both the up-front and ongoing damage of this spell.

The target gets a health save.
Fail: The target takes 1d4 acid damage, and 1 armor damage.
Pass: The target takes no damage.

Cantrip:
You cannot Intensify this spell.