Hellfire

Many warlocks make pacts with fiends. But there is only one fiend that can grant a warlock with the ultimate destructive power, Mephistopheles. Warlocks of Mephistopheles favor may be granted the use of Hellfire. A type of fire that burns hotter than any else that can burn even the oldest of red dragons. The price for this power is just the life force of the caster itself. 

Hellfire Infusion

You can imbue your eldritch blast and fire spells with the power of hellfire. This ability can be used a number of times equal to half your warlock level rounded down to a minimum of 1. Hellfire adds 2d6 fire damage to the ability or spell. Hellfire burns hotter than any fire and is all consuming, this fire damage ignores fire resistance and fire immunity is treated as fire resistance for the target. Using hellfire requires sacrificing some of the casters life essence, whenever this ability is used the caster takes 1d4-1 CON damage. This CON damage can only be restored by means of a long rest.

 

The damage hellfire does increases to 3d6 at level 5 and 4d6 at level 10.

Devour Magic

Starting at 6th level you can devour magic. This lets you cast dispel magic or counterspell without using a warlock spell slot. If you successfully counter or dispel a magical effect you restore the use of one warlock spell slot. 

Once you use this feature, you can’t use it again until you finish a short or long rest.

Infernal Toughness

Starting at 10th level, you gain the tough feat. The benefits for this feat only apply to warlock levels. 

Brimstone Blast

Starting at 14th level, when you infuse hellfire into one of your spells or Eldritch Blast you only take 1 CON damage instead of 1d4-1 CON damage