go kill your self

How annoyingly fun lol. Anyway just a few suggestions. I think you need another win condition. It's too easy to get rid of door to nothingness these days with all the countermagic and artifact destruction. I know you run elixir of immortality but I think you need to have something else in there in case. I would suggest adding some more countermagic and some mill to the deck. Below are some cards that I think would work marvelously:

Traumatize - exile this card to Elite Arcanist to erase their library very quickly
Seeker of Skybreak - use Elite Arcanist more than once per turn
Doorkeeper - defender and a milling machine
Counterspell - shouldn't have to explain this one
Dissolve - similar to Counterspell but costs 1 colourless more and you scry 1
Tormod's Crypt - to make sure they don't use something like Elixir of Immortality
Asceticism - Hexproof your key creatures so they can't be bounced or killed

I would get rid of Dispel, 2 of the 4 elixirs, and swap archaeomancer for mnemonic wall since it works better with the defender theme and has the same ability. You may also want to consider a draw engine just to make sure you get what you need faster. Maybe something like howling mine, rhystic study, stroke of genius and/or sphinx's revelation since you can generate any colour with axebane guardian, and if you can pop Tamiyo's ultimate, you won't have to worry about discarding either.