[Thor]

He killed you first and the game bugged and completed the attack turn but you really didn't do that last hit. The same as when some hits for over 100% of accuracy.

Seems the more logical answer to me or it's simply a bug and Eagle has the immortality ability?

p.s. I'm sure not a lot of people knows or remember but some players were given bonus hp as a reward to winning contests. Can't say I remember Eagle getting 1 of those though.