Bear with me. I realize this card is unlikely to do much due to its cost. Still, like we talked about back when Worst Fears was spoiled, it's interesting to think about how much is the upper limit for powerful, playable effects in Vintage. Six mana is a really, really, high price and its really, really bad for Vintage. However... we do actually play cards with this cost, namely Dragonlord Dromoka.
Pushing aside the casting cost for a minute, the first two abilities of Ajani are really good. The +2 ability is the business end of Ancestral Recall (best draw spell in Magic). You lose the ability to get lands in your hand this way, which hurts if you need cards in your hand generally for brainstorm or something else, but you get the gas. The -2 is Swords to Plowshares (best removal spell in Magic).
The third ability sets up poor Ajani to be much worse than Dromoka, probably. It doesn't win on its own, unlike the Dragonlord or basically any other Vintage-playable Walker. I have to imagine that you are going to be Ancestral Recalling yourself instead of making your creatures bigger. Add to that the fact that Ajani does not protect himself anywhere near as well as Dromoka, so he's probably doomed in Legacy / Vintage.
So, here's the question. In the abstract, what is the maximum we could pay for a card like this? Something that is alternatively the best draw spell or the best removal spell in Vintage?