Elementalist

Prerequisite: An ability or spell that lets you deal a form of elemental damage.

When you gain this feat, you gain the following benefits:

• Spells you cast or magical abilities you possess ignore resistance to one of the following damage types: acid, cold, fire, lightning, thunder.
• When you deal a critical hit with your chosen damage type, or a creature rolls a natural 1 on a saving throw against an elemental effect you created, the target suffers additional effects from the list below:
  
  

  Acid: Target takes an additional 1d4 points of acid damage from all attacks until someone takes an action to scrape it off.
  Cold: Target’s speed is reduced to zero until then end of it’s next turn.
  Fire: Target catches fire, taking 5 (d10) fire damage at the start of their turns until someone takes an action to douse the flames.
  Lightning: Target is electrocuted, causing it to have disadvantage on all of it’s ability checks and attack rolls until the end of it’s next turn.
  Thunder: Target is knocked prone and is deafened until the end of it’s next turn.
  
  

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