This card seems underpowered for a mythic, considering the Woolly Thoctar, an uncommon from Shards of Alara, is a 5/4 for a similar mana cost. The keywords help recover some of that cost, but they don't give it mythic power or flavor. Also, considering the high amount of power creep that MTG is susceptible to in successive blocks, this would, at best, only be useful in draft.
I made this guy a while back, and I always thought he would be really powerful. I see your point, and welcome any suggestions to improve his badassness. Make him indestructible, maybe?
I would say make him a 5/5 and give him Regeneration instead of Lifelink. Or trade Lifelink for Vigilance, while still maintaining a B: Regenerate this creature.
5/5 might be a bit too big for 3 mana. Let's make him a 4/5 and throw B: Regenerate on there, too. I'll make an updated version.
The words are out of order and can be put on the same lines with commas.Haste, lifelink, vigilanceB: Regenerate ~.