Elemental Master (Acid)

When you gain this feat, you have become a Master of Acid. You gain the following benefits

• Spells you cast or abilities you have that deal Acid damage, ignore resistance. In addition, when you roll damage for a spell or feature that deals Acid damage, you can re-roll any 1's and 2's rolled, but you must take the new value
• You gain immunity to Acid damage 

Additionally, as an action, you can create a pool of acid covering a 15ft square on the ground in front of you that lasts for 1 minute. Any creatures that start or end their turn in the pool of acid must make a DC 14 DEX Saving throw taking 3d8 acid damage on a failed save, and on half as much damage on a successful one. You can use this ability once per short rest

• You can select this feat multiple times. Each time you do so, you must choose a different damage type.