Legit loop?

[Avodroc13]

 {Blood Bairn}'s ability +  {Gravecrawler}'s ability + a zombie on the battlefield & enough mana to do it. Is it possible to sacrafice Gravecrawler w/ Blood Bairn's ability over and over and over and stack up on +2/+2 counters as long as you have the mana to keep bringing gravecrawler back?

[scarsabrex]

Yes it is legal

[Paraluke]

To be sure,  {Blood Bairn} gets +2/+2 until end of turn, not +2/+2 counters.

And since you can only cast creatures in your main phase, it can only get to its biggest during your main phase.

[Agrus Kos, Enforcer of Truth]

The combo works the same if you use {Tenacious Dead}. The combo costs a little more but it only requires two cards ({Blood Bairn} and {Tenacious Dead}) and will be legal longer. A few guys from my LGS figured it out during the prerelease and dominated with a G/B aggro.

[BcBudds]

Works quite well with grimgrin although he's not legal long