hello
while there can be a loot of powers a loot of different options i would like to suggest a power use option in the way you can use your powers
ex shield you can make protective shield that protects an ally or hold the spell button to channel the shield to make it stronger using your mp or supercharge if the game has it to keep it up
also by targeting an enemy you can stop the enemies attack like stopping boss from using wide floor smash and doing aoe dmg to all and things like that
or if you want to stop enemy from taking some item you can put up a shield on it so that it first needs to be destroyed for enemy to be able to take it
option to make your spells single or aoe target so fireblast can attack one person when you want or swich to aoe and fireblast canattack everyone in 5yd radius of that person
these are a few suggestions that i hope would help developers
"Azarath, Metrion, Zinthos"
It sounds like most of what you're describing is going to be addressed by the Mechanics/Asthetics separation that the devs are currently planning on.
The "shield" power will likely be a general Self+others deffense buff set that you can choose to animate with a Shield animation.
The single-target and multi-target Fire abilities will probably be separate powers within the same set. What powers you choose to take within a power set will be up to you.
Sic Semper Tyrannis