[quote=Tyki]
the fact that ysmir can actually kill him if required...
[/quote]

Not really. You even so much as start using magic, and he's in a different time, and you're dead. And through harnessing time, he can quite easily freeze you in time, or reverse the time on his organs, healing them. Even if you destroy the heart, it's 16 seconds to brain death on average, giving him sufficient time to simply travel back in time. Furthermore, he's been in the future. Thus, if you ever planned to kill him, he already knows, and he'll have taken preparations.