Corrosive Bomb

You hurl a bomb of concentrated acid at a target. The blast of said bomb coves a ten feet sphere. Any creature caught in the blast radius must make a DEX save.

On a failed roll, any target in the blast of the acid bomb takes 3d4-1 damage and loses (2d4-2)/2 of armor class rounded down. 

On a succesfull roll the target must take half the damage and its AC is unchanged.

The loss of armor class only applies if the target has medium, natural or heavy armor. If the target has light armor, on a failed save it loses 1d4 -2 AC instead. 

In the event that the target has a resistance to physical damage, the acid bomb nullifies this instead of affecting the armor class. In the event the target has a physicall damage inmunity, a failed save roll will downgrade this to a resistance instead of affecting the armor class

Inmunity>resistance>AC

In the event that the target has resistance to acid damage, this spell has no effect.

A creature can only be damaged and affected by this spell once per day.

At Higher Levels. When you cast this spell using a spell slot of 3th level or higher, the damage increases by 1d12 -1 for each slot level above 2nd and the loss to AC increases by +1 for every 2 spell slot level rounded  down.