Selfless Squire 3W
Creature - Human Soldier
When Selfless Squire enters the battlefield, prevent all damage that would be dealt to you this turn.
Whenever damage that would be dealt to you is prevented, put that many counters on Selfless Squire.
Any human with flash deserves my attention, even at 4cc. But I'm pretty intrigued about the "Whenever damage that would be dealt to you is prevented, put that many counters on Selfless Squire." part. Does it mean that if you attack me with a 5/3 it becomes a 6/6? If you attack with a 6/6 mentor aand 3 monks 5/5 this is a 21/21? Then well, this can be something. Not against tokens strategies, but this could be something against aggro decks.
Looking at it again it seems pretty lame for vintage, only decent against certain decks, and nothing special without evasion or something spicy to do with counters. Of course I assume there is no "fog deck" available, where this could grow to nasty proportions.
I suppose this has little possibilities in vintage, but seems an interesting card