The thing about Magnus is that his mana is ASS. Arcanes are not an option, but mandatory, and that already locks him out of 8 STR/25 IAS. You could just get a carry with HotD and keep a manaburning satyr or whatever it was around and he'd be limited to tossing around two Shockwaves (or an Invoker with EMP lololo so skill rite guyise).
Or... maybe just spread a bit around. Reverse Polarity does not have much of an AoE.