Enchantment, 1W (2)
Uncommon
Each creature you control with a level counter on it gets +2/+2.
No one spoke. There was no need. The threat of the Eldrazi presented a simple choice: lay down your weapons and die for nothing, or hold them fast and die for something.
Illus. Kekai Kotaki

6/15/2010: Each creature you control with a level counter on it gets just +2/+2, regardless of how many level counters it has. It doesn't get the bonus for each counter.
6/15/2010: Time of Heroes affects any creature you control with a level counter on it, not just levelers. (Of course, it's pretty hard to get level counters onto a creature that's not a leveler, but it can be done with copy effects, Fate Transfer, or Quicksilver Elemental, among other possibilities.)
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern