Mac book alu can support all the latest high end game for now.
No worries for dota=D
Just that it will get a real hot on the left side of your macbook cause that's where all the important stuff of the mac is located.

Other than that,everything is good to go.
If you want to play dota,i think you might need another keyboard for the hotkeys?
Or you can get dota warkey =X

Cheers.