Any CLUE what show this is?

Hows it goin everyone? Does anyone know what show has an episode where at the end of the episode there is an old man/wizard or something and they are inside either a cave or a creature, and he was evil but turns good at the end. Right when that happens he sends a little boy, or other character away in some sort of mystic bubble saying to the kid " This is not for your eyes" or something like that, and then u see the old mans hand with a knife in it in the air and then it comes down. It was a kids cartoon, the old man killed himself b/c shedding his blood was the only way to stop something. I know this is a VERY vague description of the end of one episode, Im asking here because I could have sworn this was a mighty max episode due to people always getting killed in the show and all that, but i recently rewatched every episode and I didnt find the episode i have described here. Does anyone at all know what show it is from? I remember it being a really good one when I was younger, but I cant remember much about it at all, I just know it was one of these kinds of cartoons with action and stuff like that. Anyways thanks for any replies, take it easy!