Skeletal Swarming

Trample

At the beginning of combat on your turn, target creature you control gains trample and gets +X/+0 until end of turn, where X is the number of creature cards in your graveyard.

Ward

If a creature an opponent controls would die, exile it instead.

At the beginning of each end step, create X 1/1 black Rat creature tokens with "This token gets +1/+1 for each other Rat you control," where X is the number of creatures that were exiled under your opponents' control this turn.

Skeletons, Vampires, and Zombies you control get +1/+1.

At the beginning of your end step, if a creature died this turn, you may pay . If you do, create a 1/1 black Skeleton creature token.

Artifact creatures you control have trample.

At the beginning of your end step, create a 0/0 red Gremlin artifact creature token. Put X +1/+1 counters on it, where X is the number of differently named artifact tokens you control.

Indestructible

As long as your devotion to red and green is less than seven, Xenagos isn't a creature.

At the beginning of combat on your turn, another target creature you control gains haste and gets +X/+X until end of turn, where X is that creature's power.

At the beginning of your end step, if you control exactly one creature, create a 5/5 black Demon creature token with flying.