Troll Ancestry

In addition to other feats taken at 1st level, as a Goliath you may take this feat as a replacement for the Giant Ancestry feature.

Your ancestry includes Troll—warped kin of true Giants—and you carry their unsettling gift for regeneration. Wounds knit shut and fade away, leaving few scars. Some with this heritage are shunned; others are feared or respected for surviving what should have killed them.

Giant Ancestry

You can use this feature a number of times equal to your proficiency bonus, regaining all expended uses when you finish a long rest.

Trollish Regeneration. Your wounds knit shut with unnatural speed, and you shake off what should have killed others. At the start of your turn, you can choose to regain hit points equal to 1d8 + your proficiency bonus without using an action. You can't use this feature if you've taken acid or fire damage since the end of your last turn, and any hit points lost to those damage types can't be restored with this feature. If you start your turn at 0 hit points and aren't dead, you can use this feature before making a death saving throw. You can't regenerate lost body parts, and loss of a head is fatal. When you regain hit points up to your maximum, no scars or bruises remain from the damage you've healed.