Do exalted or WoD do typed bonuses? I don't really see anything about it, but the dnd approach seems fair for peer magic like that.
No stacking say the magic version of nitro boosts, but a tool that you can "paint" a spell pattern into and set it to cast it with you later so you don't need to hold as much in your head at once for example wouldn't functionally overlap.
Not exactly, we didn't get an age for it directly. What he did was still pretty bullshit though. He used time travel to build the whole thing at once in 5 different (presumably synergistic) ways at the same time.
I'm not saying he wasn't bullshit, but he was still a mortal wizard who got a leg up with training from Odin. He had great talent, but nothing he did was in principle impossible for any other wizard to replicate.
From the wiki it would kill them with
banefire.
That he needs a huge magic bomb engineered into a construct instead of killing them directly, and that it would have such awful collateral, implies he couldn't make it work in a fight though.
At a guess it's because Dresden Files true immortals cannot be killed outside of Halloween, they'll just come back regardless of what you do. Even if you do kill them then their mantle will probably bond to another host unless the killer does stuff to it.
We know that Merlin was using time magic, so it wouldn't surprise me if he somehow twisted it so that the stasis traps prisoners in a frozen moment stolen from Halloween.
No seriously, Ethniu was explicitly operating on a timer till the white god nerfed her into the ground. That was the win condition of the fight.