-facepalm-
Apparently I totally forgot (twice) to add the most important part: I'm looking for an adventure, roguelike or RPG game; I already know about a lot of fighting games that fit the description (mainly those you talked about).
Magicka!
You have to learn a bunch of keypresses that combine together to strengthen your abilities.
The monsters are brutal and you'll find yourself leaning towards the best combo in all likelyhood.
You can blow up your friends in either co-op or an arena mode, both of which work seem to work decently well.
Blowing the shit out of your friends is considered an acceptable loss, and highly balanced too.
There's a new worms game called worms WMD where you can craft better weapons with parts. If you've ever played Worms Armageddon it's like that but better.
I actually can't think of modern games that encourage you to spam one ability though. Maybe Destiny? You get a handful of really cool powerups from levels.
It's Halo but with magical powers. The best jump in and FPS grind with friends, ever made. It's made by Bungie. It's also an MMO servicing PC and most consoles.
Top tier Co-op.
https://www.bungie.net/en/Help/Article/12219In Spelunky bombs are your best weapon. Once you learn to hit things with a thrown bomb without using paste you've mastered the most powerful tool in the game.
In most of the games I play there just isn't one strategy because that would be repetitive.
In Skyrim you can invest everything to become a glass cannon, in one ability. Nothing is that much stronger or weaker though. Also I think maybe the combat difficulty scales with how many skills you choose to invest in. Oh yea FUS ROH DAH is fucking awesome. Max that shout to have the most fun.
In Terraria you just invest in ranged all day. That can carry you from the beginning of the game to the end. Terraria is 2d Minecraft. With guns.