Deadly Grub

Vanishing 3 (This creature enters the battlefield with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Deadly Grub dies, if it had no time counters on it, create a 6/1 green Insect creature token with shroud. (It can’t be the target of spells or abilities.)

Lavacore Elemental

Vanishing 1 (This creature enters the battlefield with a time counter on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a creature you control deals combat damage to a player, put a time counter on Lavacore Elemental.

Martyr of Bones

, Reveal X black cards from your hand, Sacrifice Martyr of Bones: Exile up to X target cards from a single graveyard.

Void Maw

Trample
If another creature would die, exile it instead.
Put a card exiled with Void Maw into its owner’s graveyard: Void Maw gets +2/+2 until end of turn.