Source: System Reference Document 5.0
The text on this page is Open Game Content, and is licensed for public use under the terms of the Open Game License v1.0a.
Experiment Feats
Abyssal Hide (Third-Party)
Abyssal Hide (Third-Party)
Devil's Arm (Third-Party)
Dretch Belch (Third-Party)
Imp's Eye (Third-Party)
Infernal Horns (Third-Party)
Infernal Mask (Third-Party)
Vrock Feathers (Third-Party)
Standard Feats

A feat represents a talent or an area of expertise that gives a character special capabilities. It embodies training, experience, and abilities beyond what a class provides.

At certain levels, your class gives you the Ability Score Improvement feature. Using the optional feats rule, you can forgo taking that feature to take a feat of your choice instead. You can take each feat only once, unless the feat’s description says otherwise.

You must meet any prerequisite specified in a feat to take that feat. If you ever lose a feat’s prerequisite, you can’t use that feat until you regain the prerequisite. For example, the Grappler feat requires you to have a Strength of 13 or higher. If your Strength is reduced below 13 somehow—perhaps by a withering curse—you can’t benefit from the Grappler feat until your Strength is restored.

Experiment Feats

Source: EN World EN5IDER, “Fell Grafts: Demons & Devils”

Simply acquiring an experiment feat immediately grants its benefits—unless the GM decrees otherwise, the actual acquisition of any following feats are narratively driven and do not require the PC to physically find and integrate a foreign body part.

However, should the GM so decree, the PC must have the part of another creature’s body that they want to make their own in order to graft it. Though this can be challenging for rare targets, a character with an experiment feat is able to express their own will on a conjured creature in order to gain the desired limb. When the summoned creature dies, the character makes a Constitution saving throw opposed by a Constitution ability check by the summoner; on a success, the rest of the conjured creature disappears but the desired body part remains for 1d4+5 minutes.

So long as a body part comes from a creature permanently on the Material Plane (or as described above) and is fresh (or properly preserved with a bag of holding, gentle repose spell, or other appropriate measures), a character can graft it onto themselves. Grafting the foreign body part on requires the corresponding part from the grafting character’s body be removed (dealing 1d10 points of damage to themselves) and a Wisdom (Medicine) check in a gruesome process that takes 5 minutes to perform. The DC of this check is equal to the grafting creature’s Hit Dice. Other characters may assist with the Wisdom (Medicine) check as normal, but attempts to perform it themselves increase the DC to 8 + the grafting creature’s Hit Dice.