Skeletal Swarming (Ampersand Promo) [Dungeons & Dragons: Adventures in the Forgotten Realms Promos]

Each Skeleton you control has trample, attacks each combat if able, and gets +X/+0, where X is the number of other Skeletons you control.

At the beginning of your end step, create a tapped 1/1 black Skeleton creature token. If a creature died this turn, create two of those tokens instead.