Thanks to your large size and amalgamate nature you are unnaturally strong and can withstand more than most living creatures.

You gain automatic proficiency for intimidation and all checks based on intimidation 

You count as one size larger when determining your carrying capacity and the weight you can push, drag, or lift (Medium is Large, Large is Huge, etc.)

Due to your undead soul, you do not need to eat, sleep, breathe or drink. Instead, you must enter a semi-conscious trance for 4 hours a day. Remaining in this trance for 4 hours a day gives you the same benefit 8 hours of sleep for a normal human would give. Additionally, you cannot drown due to the fact that you don't need to breathe, but you cannot swim either as creatures such as yourself tend to sin

Due to your undead soul, you do not need to eat, sleep, breathe or drink. Instead, you must enter a semi-conscious trance for 4 hours a day. Remaining in this trance for 4 hours a day gives you the same benefit 8 hours of sleep for a normal human would give. Additionally, you cannot drown due to the fact that you don't need to breathe, but you cannot swim either as creatures such as yourself tend to sink.

You're allowed to graft any part of a creature you killed to your body under specific conditions:

1) You must pass a Medicine check with a dc equal to the base armor rating of the creature when it was alive for most parts. For small parts like horns and tusks, the dc is half of the armor rating.

2) You must replace one of your limbs with said grafted piece, certain exceptions are allowed such as horns or tails.

Upon grafting the parts to your body you gain various bonuses. Depending on the species some parts may have special effects, but most parts share these traits:

Arms: +1 to Strength and Dex saves/checks per arm grafted

Legs: +1 to Athletics and Acrobatics saves/checks and +5ft of movement per leg grafted

Tails: You gain Advantage on rolls made against your balance (i.e being knocked over or falling)

Heads: If you replace your Arm with a head gain the normal arm bonus as well as a limited use, non rechargeable spell based on the creatures main attack (Dragons grant fire breathing, Basilisks give poison breath, etc.)

If you fail the medicine check at any point, you butcher the part and cannot graft it to you and must make another medicine check to reattach the original part, if this check is failed it must be mended by a healer or another character with medical proficiency.

The sutures binding the parts of your body may grow frail, if you take enough damage your body may fall apart and require reattachment via a Medicine check (dc is 10). This can be avoided by passing a Constitution save (dc is 8 when not in combat, 10 when in combat) before the part falls off.