Card Spotlight
A {2}{B}{G} 3/4 that gets an experience counter whenever another creature you control dies. At your end step, it returns a creature card from your graveyard to the battlefield if its mana value is at most your experience count, or to your hand if not.
Commander Spotlight
Meren of Clan Nel Toth ↗
A {2}{B}{G} 3/4 that gets an experience counter whenever another creature you control dies. At your end step, it returns a creature card from your graveyard to the battlefield if its mana value is at most your experience count, or to your hand if not.
See Meren of Clan Nel Toth's full stats and printings →
As a Golgari commander it's a value engine that returns a creature every turn it survives, and it gets stronger as the game goes on. It's a well-known commander, so expect opponents to remove it early, and plan to recast it.
In the 99 it's a strong card in any black-green sacrifice deck, though it's at its best in the command zone, where you can rely on it every game.
Viscera Seer ↗
A one-mana sacrifice outlet that scries each time, turning any creature into an experience counter.
Eternal Witness ↗
Returns any card from your graveyard to hand when it enters, and Meren can return it every end step.
Sakura-Tribe Elder ↗
Sacrifices itself for a land, earns an experience counter, and comes back to do it again.
Blood Artist ↗
Drains a player for 1 whenever any creature dies, so every sacrifice also deals damage.
Inexpensive. Meren has been reprinted several times, including in Commander Anthology, Commander Masters and Tarkir: Dragonstorm Commander, which keeps the regular printings cheap.
Two or three is enough to return a cheap value creature to the battlefield every end step. Experience counters stay with you for the rest of the game, so the cap on what Meren returns keeps rising.
It goes to your hand instead of the battlefield. You still get a card back every end step, it just costs mana to cast.
Yes. Experience counters are on you, not on Meren, so they're still there when you recast it.