All the ones in the official list at least. But I think we need twice that many.
I'm guessing this was in regards to spells.
Yes, you will Need a LOT of different spells. An example of spells/powers that may be inspiring is 4th edition powers, for all 26 classes. Each power in a sense functions as a spell, in that it's an attack of some kind or some variation on it. And there are thousands and thousands of powers now for all the classes.
Maybe glancing through them, for inspiration... would be worth your time. (An easy way to do this is get a DnD Insider subscription, download the character builder, and then run the Quick Character option, set them to level 30, and then go look at that classes levels and read the various spells.)
See in 4th edition D&D they really made it so that a fighter has an attack, and a wizard has an attack.. neither run out of power. But those same classes also have encounter powers.. powers usuable only once per encounter, (simple math to avoid extra complexity, by 30th level a character will have 2 at-wills, 4 encounter powers, and 4 daily powers, and 7 utility powers. But as they go through the progress, levels 1-10 is heroic, and building their base powers.. level 11-20 is Paragon, kingdom level events, and you begin to replace earlier level powers with new ones, encounter and daily, and level 21-30 is epic level, you still are replacing earlier encounter and daily powers, but now the powers are appropriately epic. And going up to epic level the at-wills scale up and do more damage now.)
All of that just gives a great way to provide interesting combat experiences.. of which you should be able to find things that are just super compelling.. more so than just a fireball.. and so on.
And this is great to hear about the monsters becoming aggressive! Thanks, I'm really excited now!