What worked for me:
3 or 4 tanks (laser, laser, plasma, & fusion)
3 Psi-amp operators (Spooky, Maria, & Christel), laser pistol sidearms
2 Blaster launcher operators (Asia & Vin) with 5 bombs each, more could be good
2 flying scouts (Crackshot Yamata and Ellen Ripley)
3 or 4 Riflemen (laser, heavy plasma)
Everyone at least in a power suit with psi strength 40 or better. I ended up with one mind-puppet but he lived and everyone stayed well clear of him.
One rehearsed blaster bomb shot to break open the access-lift pyramid & allow tanks inside.
One lucky blaster bomb shot that knocked out a sectopod, a snakeman, and a hidden chryssalid in one go.
One lucky storming of the final lift with a fast-reaction trooper, when all the ethereals happened to be turned away. Psi troopers were on standby. Psi-controlled them at will.
One package of high explosive: $300
Watching the alien brain sweat as the timer ticked down: worth it