How do you get this spell?

It's near the end of Tidus' sphere grid. Just keep 'leveling' Tidus and advancing along his sphere grid and you'll get it.

How do you know it's the end? Some of my characters have overlapped other characters sphere grids.. there are multiple ways of going to sphere grids

It's on the left side of the sphere grid.

Or you could go to say... gamefaqs or a similar site, and look for a JPEG for the entire sphere grid.

Or you could press SELECT on your controller and move your cursor around the grid looking for it yourself.

Once Tidus learns it have some friend spheres handy, cause hastega=great.

Or get some master spheres and activate hastega like that though its one very usefull spell.

Well, using Master Spheres to get it is a bit excessive especially once you've got to the Monster Arena you can then bribe a Machea (for 450,000 gil) for loads of Chocobo Wings (I usually get between 50-60 per fight) once you have 80 Chocobo Wings then you can add Auto-Haste onto a piece of armour, and seeing as almost every Ultimate Weapons and Armour guide says to put Auto-Haste onto your ultimate armour, then this should be the best way to do it especially as those Master Spheres are very rare.

Yes, Auto Haste is the way to go. With Break HP limit too. You can get such armor by killing Nemesis.

Why did you bump this?

Because the threads are all so old here compared to other sites. I am sorry.