Just a quick add for Dr Strange:
The above tips work great, but if your still having problems then you can add Asgard Armor and when Black Magic doesn't turn the Mephisto Pets or a leaper (prior to the bridge) into a box you'll put them down a lot quicker.
Also, when you take down the last Fire Giant and kill him with his own sword, try to bash him and not the walls too. When you get in with Mordo you should be able to take down his health 50% with the sword alone. Then use your extreme, then fly around and Black Magic him. Try not to miss with the Black Magic, you don't regenerate energy while flying, and you need to hit him a few times to get more energy balls. I only landed one time, avoided him while recharging, then flew again and killed him. 20,360... The recharging part cost me about 30 seconds...
You don't have to fly if you're good at spinning around and hitting him with Black Magic while running away from him constantly, but I think flying is easier.
Thanks for all the great tips here that I used.