Try this mage to maybe self sacrifice. Maybe if hes in a group he grows fond of them and during a battle where its either he dies in glorious battle to save his companions and joins his deity in eternal glory or everyone but him dies.

Only way I can see it justified

Good idea, but it would make not a lick of sense in context.
There's nothing stopping him from just walking up, killing Mr. MacGuffin stone-dead and that way securing victory for himself.

That's exactly my problem. I need him defeated and killed when there is nothing to stop him. I fucked up.

When all else fails.... Unstoppable lava-puking sword-swinging Cockmonster...


Or have him meet another extremely hard to beat foe. Maybe somebody he met in his past? Something so powerfull even he has difficulty fighting it. Then maybe they kill eachother?

love interest betrays in the middle battle of the with a stab in the back

No such thing.

what if a character earlier in the story who refused to help comes in to help giveing them just enough of an upperhand to beat the guy. (I.E. Han Solo showing up late for the party) just an example, not really what i had in mind but something along those lines

That could work. I'll keep that in mind.
Thank you, kind stranger!

no problem. i have an abhorrence for writing/english but i am very good at it. i think my abhorrence is rooted in the fact that all through school you never write anything creative. it always ends up being an essay or assignment. i do a lot better and enjoy more the creative writing type stuff. i was trying to think of something that hasn't been done as often. when i thought about it the only example i could think of was Han solo so i thought it'd work...

quick question:
is the evil mage the protagonist? (not necessary except to answer my curiosity)

if you give me some of his most common or most powerful abilities, some of his accomplishments, maybe a bit of a bio, his enemies abilities, any key traits of his enemies (ex: they are extremely determined, they can take a great amount of damage), then give me a few hours (possibly a night) to daydream and i might be able to come up with a couple of possibilities

might want to message these to me if you don't want too many details made public

You just spoilered The Godfather for me.

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Main character finds some hidden secret about the mage guy, finds weakness, epic battle, boom mage guy dead.

Mage guy is one of the main characters.
I need the antagonists to win and can't make it happen.

If he's a tank, speed should be one of his weak points. You can use the classic "Never trade speed for power" idea.

If he's been dominating through out the story, you could give him a tragic character flaw like arrogance. Think of Vegeta vs. Cell. Vegeta kicks the shit out of him, gets cocky and allows Cell to absorb 18, then gets his ass beat.

Maybe the deity gets summoned, kills the mage because it doesn't want to owe him anything, and the mage's enemies figure out how to reseal the deity.

Just throwing some ideas around.

Those are excellent ideas, and I can't use any of them. Each one breaks consistency somewhere in the story.

It's too easy to move himself with telekinesis for that. One of the reasons he can wear armor that heavy in the first place. Still, I'll keep this in mind.

Thing is, his opposition really has nothing left to stop him with. He himself has been critically wounded and is on a second wind rampage to kill the MacGuffin person.
I could easily let him collapse and die afterwards, but that MacGuffin needs to stay alive at all cost or it's the whole plot that collapses.

The deity does get revived later, but the tank mage must be dead by then.
Actually it's his death that indirectly leads to the resurrection a bit later. It can't be a self-sacrifice though, as he couldn't know that would happen.

Thank you very much for your input and taking the time to respond.
Maybe I can construct something.

I don't know, have them find some artifact of some sort that gives them an upper hand? i.e. Flame retardant, force field, enchanted sword

There is an artifact, but that's reserved for the deity or I'll have no way to get rid of that one.
Against the god it's the only way, but against the tank mage it would again cheapen the victory.

What I need is a clever, breathtaking-awesome way of killing someone you have a snowball's chance in hell against.

Are the people who are trying to kill the mage guy adventurers or warriors? If so, the mage guy could do something like knock them to the ground, and they could shoot and arrow at him. It misses/he dodges, it hits something, chain reaction occurs and something hits/falls on the mage.

Two "regular" mages and a handful of soldiers.

Tank mage has butchered those by the dozens throughout the story and now I need a plausible reason for him to suddenly lose when he's actually at his absolute strongest for long enough to off them all.

How about the deity turns on the evil mage, as he no longer needs him?

Tank mage must die before deity returns.
His death sets of a chain reaction.

Damn, then I don't know. This seems to be a pretty in depth story.