Skeleton Shard

{3}, {T} or {B}, {T}: Return target artifact creature card from your graveyard to your hand.

Sanitarium Skeleton

{2}{B}: Return Sanitarium Skeleton from your graveyard to your hand.

Don't Have

Necrobite

Target creature gains deathtouch until end of turn. Regenerate it. (The next time that creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Gutterbones

Gutterbones enters tapped.
{1}{B}: Return Gutterbones from your graveyard to your hand. Activate only during your turn and only if an opponent lost life this turn.

Clattering Skeletons

When Clattering Skeletons dies, venture into the dungeon. (Enter the first room or advance to the next room.)

Restless Bones

{3}{B}, {T}: Target creature gains swampwalk until end of turn. (It can't be blocked as long as defending player controls a Swamp.)
{1}{B}: Regenerate Restless Bones.

Manor Skeleton

Nuclear Fallout

Each creature gets twice -X/-X until end of turn. Each player gets X rad counters.

Skeletal Crocodile

Death's Caress

Destroy target creature. If that creature was a Human, you gain life equal to its toughness.

Urborg Skeleton

Kicker {3} (You may pay an additional {3} as you cast this spell.)
{B}: Regenerate Urborg Skeleton.
If Urborg Skeleton was kicked, it enters with a +1/+1 counter on it.

Skeleton Scavengers

Skeleton Scavengers enters with a +1/+1 counter on it.
Pay {1} for each +1/+1 counter on Skeleton Scavengers: Regenerate Skeleton Scavengers. When it regenerates this way, put a +1/+1 counter on it.

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

Kjeldoran Dead

When Kjeldoran Dead enters, sacrifice a creature.
{B}: Regenerate Kjeldoran Dead.

Marang River Skeleton

{B}: Regenerate Marang River Skeleton.
Megamorph {3}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)

Skeleton Ship

When you control no Islands, sacrifice Skeleton Ship.
{T}: Put a -1/-1 counter on target creature.

Drudge Skeletons

{B}: Regenerate Drudge Skeletons. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Have

Uchbenbak, the Great Mistake

Vigilance, menace
Descend 8 — {4}{U}{B}: Return Uchbenbak, the Great Mistake from your graveyard to the battlefield with a finality counter on it. Activate only if there are eight or more permanent cards in your graveyard and only as a sorcery. (If a creature with a finality counter on it would die, exile it instead.)