Me and my friend play 3 diff 2v2 combos.

QoT+Sedna = unkillable more or less since start if played right and by that you can just herass the enemy till you hit warscore 10 at which point u buy giants and help push with them and it's GG, yet to lose with this setup

2 x Lord Erebus = Usually played on prison to make best use of bat swarming to dominate the map, if the enemy over strech we go for a a kill but the general idea is to make the opponents scared so asap they see one of us they retreat cause they know the 2nd Erebus is't far behind. Lost once vs Sedna and UB

2 x Regulus = Play it super safe till lvl 7 at which point you get mines rank 3 and HoL, Then more or less steamroll anything, we use 0 gold on the citadel with this just items to the demigods, not lost with this setup.

QoT + Oak. No matter which one you attack, they spend all their time invulnerable. Bramble -> shield -> bramble. All 3 of us couldn't kill either of them, even all focused on the same target.

Rook + UB ->  Roll, Grasp, Slam...yeah you're pretty much fcked on that one.

Oak + Reg -> Oak's Pentinence + Reg's main allows Oak to stick on the enemy and of course Pentinence + Snipe is massive damage with the right builds.

QoT + Sedna ->  Healing, shielding, when does it end.  Hopefully you can draw them out in the open and interrupt/switch targets or just run them oom.

Rook + Reg ->  Simply retarded on Crucible.  Tower rook + mine/snipe Reg will make you pull your hair out.  Reg snipes you in a nice little portable fortress and if you come close you get blown the fck up and sniped before touching a tower.  The one combo I haven't  found an answer for in 2v2 and, thankfully, one that I haven't seen a lot of.

i was surprised how well 3rooks did, lots of same demigod is not a bad thing. i dont mind having same demigod it can turn out well on some maps.

trow in a ice TG in most teams and its the better for it.