Who here plays Warframe? Two bosses come to mind immediately,although one might not count,as it involves abusing Pathing AI.
-The Phorid. Picture a mutated dog,about the size of an RV. It can scream,harming every player on the level,and completely disabling them until the scream is done. Thankfully,the Phorid itself is ALSO locked down for the duration. It can fire homing psychic bolts,which deal an obscene amount of damage. It moves fast,and when it smacks you,it deals an obscene amount of damage,and knocks you over.
All-in-all,a VERY nasty boss. Or so I heard.
The Phorid's arena is a helipad with some miscellaneous junk on it,including two fairly large crates with a man-sized space between. So I thought "Self,I bet I can get the Phorid hung up on that."
And so I did. The Phorid always opens up with a scream,and will only use the bolts on targets beyond a certain distance. I take the scream,and make a beeline for the crates,getting the Phorid stuck on the gap. Too close for the bolts,too far for the swipe. And it won't scream again,because it thinks it can get me.
-Lieutenant Lech Kril. He's huge,he's very well armoured,he has a minigun with infinite ammo,and a hammer the size of the short bus. If he swings that hammer,there's a big shockwave that probably just knocked you over. If he drives it down,he just sent a wave of ice at you. He can also fling ice spikes. Oh,and did I mention that he's INVINCIBLE!?
Yes,the boss that cannot take damage...Conventionally. Many players have a hard time against Kril because of the fact that you have to first get behind him and muck with his cryopack. By shooting it until it turns green. But that's not all you have to do. Once it turns green,you have to cut one of the hoses by shooting them,and then goad him into throwing an ice wave. Rinse and repeat three times.
Once all four hoses are cut and he accidentally froze himself for the fourth time,he ditches the ice for fire. And then he becomes your average bullfight boss.
Most players find Kril hard because of his raw damage output,and the fact that to fight him,you need to be in the open. Me? I just stay in arm's reach. His AI dictates that he has to swing his hammer at that range. The arm goes up,I roll out of range,then I shoot his backpack. Easy pickin's.