Creature — Insect 3/1, 2B (3)
Common
Vanishing 3 (This permanent 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, put a 6/1 green Insect creature token with shroud onto the battlefield. (It can't be the target of spells or abilities.)
Illus. E. M. Gist

2/1/2007: The ability checks to see if Deadly Grub had no time counters on it at the time it was put into a graveyard from the battlefield. This doesn't necessarily mean it must have been sacrificed due to vanishing; it could have been put into the graveyard some other way (say, while the sacrifice ability of vanishing is on the stack).
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern