I was playing as Pavium on a 2v2 match and I've thought of a plan that seemed bloody ridiculous, but I believed it was worth a shot. I've gathered enough resources and energy to build a base with nothing but Mega Turrents and had all of them upgraded. Along side were two shield generators, one turrent, and one sensor tower and it COMPLETELY DESTROYED the enemy ground units. Sure I know it was a troll base (it was funny as hell to harass the enemy), but unless they had air units (had reavers to counter that issue) to attack the MTs (Mega Turrents), it was damn near impossible to attack my base.
Yeah that's the enemies fault for allowing it to get that a full base of Mega Turrets is extremely expensive. Usually when 2-3 Mega turrets are up the main priority is always the Mega Turrets by all means, especially when they are upgraded.