Chemical Monster (5e Subclass)
From D&D Wiki
Others are born in the wilds, in the mountains or in a village in other secluded place, hardened by the harsh environment and savage beasts living around. But you have become a monster, with strength from the same source - the rage. However it is the chemicals that were applied to your body that granted you these strength, and, willingly or not, you are now the Chemical Monster.
Imbued Vitality The chemicals in your blood make your body recuperate faster. At 3rd level, you gain one additional d12 hit dice permanently. Also, when using hit dies to heal yourself during a short rest, minimal result of those rolls is 3.
Chemical Rage Your body is an inhibitor of whirling chemicals, which start boiling whenever there is an opponent to slay. At 6th level, on your first round during combat, your initiative is increased by 3 and you automatically spend your bonus action to enter rage. Also, while raging, you gain a bonus of +3 to attack rolls and your movement speed is increased by 15 ft.
Acidic Blood At 10th level, whenever you are dealt damage by a creature who is within 5 fts of you, that creature must succeed on a dexterity saving throw (DC equals to 8 + proficiency bonus + your constitution modifier) or take as many dice as the number of attacks made on you. The damage dice are d6 acid damage. This damage increases to d8 at level 13, d10 at level 16 and d12 at level 20.
Final Form The chemicals in your body are now boiling with your rage - starting from 14th level, for as long as you are raging, you are immune to acid damage and your attacks deal bonus acid damage equal to the Acid Blood's damage.