About offensive use of operator.
The skills DRAIN_EXTENSION, OBSTRUCT_SPAWN, OBSTRUCT_TOWER and to a lesser degree DRAIN_SOURCE will be used in hostile owned rooms, which for end-game players basically means RCL8. With 6 towers this means up to 3600 dmg each tick. With range and OBSTRUCT_TOWER this can be reduced a bit, but usually you have to account for at least 3000 dmg each tick. A T3-boosted healer with 30 HEAL can heal for 1400 each tich, which means you need 3 at melee range. If the defender has active defenders or PC (with OPERATE_TOWER) it is even more tricky keeping the PC alive.
What I'm saying is that PCs also need some sort of dmg-reduction to be viable in the offense.
The SHIELD is up to 25k every 20 ticks, which means a bit over 1k reduction every tick. But it requires energy and is stationary. It can help a bit, but not enough to counter a well defended room.
The OBSTRUCT_TOWER as it stands now only reduces one towers output by 50 %, which is not that useful. I think this should at least obstruct all towers in the room, if not it will be useless at RCL7 and RCL8.
DRAIN_SOURCE is underwhelming, it basically means disabling one source for the opponent for each level. I think this should be changed to BLOCK_SOURCE that extends the cooldown with a huge amount. Dedicating a high level PC to just disabling a few sources seems to have little effect. Parking a normal creep with harassment-code seems to be a better choise.
The OBSTRUCT_SPAWN is meh, expensive to maintain and only delays active defenders by a little bit. I think it should have a much larger debuff, like 100s of % at lvl 5.
My attempts at designing an offensive operator results in a very expensive (in power level-terms) creep with underwhelming abilities of making a small shield, reducing tower dmg of one tower, and delaying spawning a little bit. The only use would be draining extensions, if it can get close enough. And it will be hardcountered by any rooms with active defenders or power creeps.
My conclusion is basically that is can be used on low-RCL-rooms, but my power levels will go to economic operators. What I would have loved to see is the ability to disrupt terminal, labs or links, that might make them viable for RCL8-fights.