I need your help getting these spells: Death, Arise and Bahamut and I think Death and Arise are at the tower and Bahamut is at that mountan but problem is there's a big desert .

I'll asume your playing the SNES version...

And I don't know of any spells named Death, perhaps Doom?

Bahamut - In Mirage Village, walk behind the pub and you will find a door to take you inside. Walk out of the pub and down the path. The weapons shop will be on your right. Go into the door on the left. Proceed to the staircase and go down. Walk south until you get to the bottom. There is a secret path on the left, take it and go up the stairs that you'll come to. Grab the black chocobo. Okay, now you are going to want to fly to the forest by the desert that is surrounded by mountains in the northeast part of the map. Land and walk north, then east until you get to the mountain with a path in it. Climb all the way to the top. Fight and defeat Bahumut and you will be able to summon him.

Arise - In Mirage Village, buy it for 10,000G

Doom - Same as Arise

:>.> I'm playing the GBA version and thanks for Bahamut.