Does anyone have any tips for completing Gray Goo in World's Wake to unlock The Exterminator? I have few Legendary or epic Gear, Limited Event Crusaders, and only 3k idols acquired, 1k of which i used to unlock tier 2 objectives to be able to unlock tier 2 event Crusaders.

My event Crusaders are:

Groklok the Orc
Sally the Succubus
Kyle the Party Bro
Larry the Leprechaun
Jack O' Lantern
Rocky the Rockstar
Snickette the Sneaky
Squiggles the Clown
Littlefoot

alright, but still, any formation advice dor the loss of DPS every 100 areas?

yow alright then.

Not really. Taskmasters are useful, but not necessary. Clicking can get you a few extra areas, but it's not a viable tactic in the long run. Consider that you should spend most of the time instakilling, when you start to slow down it's time to reset. It makes no sense to wait hours to advance a few areas, when in that time you could clear hundred of areas in another run.

You should have at least 1 taskmaster, though. It will level up your main DPSer when you're away, increasing the effectiveness of your farming.

4 are even better

What I usually do is using a formation built for speed (but you don't have crusaders that boost that), and only near the end switch to one that maximizes DPS, which uses clicking and taskmasters. Auto-clicking at 10 clicks per second each is surely helpful with clicking crusaders, but as I said, this helps you push a few extra areas, it doesn't make staying on an objective a long time viable. If you can't instakill for the whole time, it's better to farm more and try again later. This is an idle game, farming will eventually become 99.9% of the game, that's what this game is about. Don't be pressured to rush things.