The magus can't work at all in 6v6 (right now), however in organized (or not) 24v24 you could go riftbot, here's a build
RoR.builders - Magus
Blue Demon on close quarters pulls, Pink one for "snipes" (blue is the optimal one...but the snipes,man...the pink is also very cute and you should most definitely use it), pop Aegis, pull, Glean Magic (it should affect everyone you have pulled), Pandemonium + Agonizing Torrent (Both should be in 0,5 sec cast time), Infernal Blast, then close your eyes, imagine those poor sods that are standing right infront of you are japanese schoolgirls, you are a rather large octopus and you are in the middle of shooting a hardcore tentacle hentai, connect your chakras, open your ki, spam the living tzeentchdamn **** out of your tentacle spanking button and then open your eyes again to witness 6 corpses standing on your feet (or 6 people standing over your corpse, or no corpses at all, it happens). Extra points for having a chosen tank with res aura guarding you and an AoE build Sorc with you, go full INT and crit because you are not a filthy midget.
Magi can actually solo roam and even emerge out of close quarter combat with mdps alive, however you will need a clever application of your CCs, an extremely accurate timing of your abilities, a liberal usage of pots, a lot of RR, and lot's of wounds to achieve victory. Here's one such build
RoR.builders - Magus
The key here is mobility (don't use the flamer however, use our pink friend instead, the pink one is kawaii as ****), cc and dots, Lot's and lot's and lot's of DoTs, due to the nature of the build and dueling in general, describing what you have to do in each situation would require me to write a novel, so i will just leave that to your imagination, however by the time you reach the required rr to pull that build off YOU WILL know EXACTLY what to do out of the sheer experience you have accumulated so far.
Finally, i suppose i should mention the good ol' fashioned default vanilla ST Havoc cookiecutter in the missionary position without double latte or cookies that is used in every other situation
RoR.builders - Magus
Not the most viable or powerful build out of there, but it gets the job done...most of the time...i suppose you know the drill, Baleful->Withering->Glean->BoC->SoI->SVF->IFoC, you build int and crit. Also use the pink one obviously. Pink one best girl. I waifu the pink one. I swear to Tzeentch that if a baka gaijin in this Tzeentchdamn thread disses my waifu i am going to get very, very mad(der).