Didn't we already just kill another card because it cost

?
No, I only remember something about a 10/9 Angel that was doomed because it could be Vapor Snagged. The Opposition Task Force failed there I am afraid.
To win bear stalemates. That said, several better options exist already. Ie. Elspeth Knight Errant pumps, has "haste," and has some proven value in Legacy.
This guy has pros if one is concerned about Thorn/Thalia effects and playing Cavern on Human. There are quirky elements that aren't apparent at first glance. It has an interesting effect against Oath; Spirit tokens trigger the ability and the Bedlam factor pushes everyone past for a swing in a "fateful hour" kind of turn. Obviously, it's good with board populators like Noble, Mishra's Factory, and Mayor of Avabruck. Potentially hilarious effects with deathtouch. Turns Thalia into a Lavamancer and Legionnaire into a Lightning Crafter. As I see it, the card is defensive in that it wards off attackers with first strike and has resilient toughness, allowing one time to build board position, and then it transforms into a finisher and board sweeper. It's slow and slightly overcosted, but on the other hand, I understand why that ability is priced that way because it's devastating if triggered. I have to test it before writing it off.