A mic is a must for this, but I'm coming from a Creative Fatal1ty usb gaming headset that's steadily getting worse.
Wouldn't expect gaming bling bling to have never been that good in the first place...
Though there's one good thing in those Creative headsets, detachable microphone:
https://imgur.com/gallery/bKU4H
Beyerdynamic's not the most fashionable design has its advantages...
Though that DT770 as fun sounding closed headphone wouldn't be good for competitiveness.
While apparently one of the better closed ones for its price in soundstage it would be still lot behind good open ones and strong "fun" bass of closed design is also too much.
But open design DT990 would be really well balanced between enough bass for fun factor/immersion (so that grenade going off nearby sounds like grenade) while having big soundstage and accurate enough sound for good level of competitiveness.
Headphones with best/highest level of competitiveness have simply "shy" or even non-existent bass leaving that part of gaming rather "empty".
Everything is simply always compromise.
While not absolutely best in competitiveness DT990 works well when combined with binaural simulation and definitely doubt that any gaming brand stuff comes even close:
https://forums.overclockers.co.uk/posts/30974164/
If you don't mind coiled cable DT990 Pro could be gotten for little over £100 if you look around.
Though only little more expensive DT990 Pro Black Limited Edition would have normal straigth 3m cable.
So with you already having usable mic for £150 you could also add Audigy Fx for Creative's well balanced binaural-simulation.
https://www.youtube.com/watch?v=d1_20T8x_OI
But obviously if environment is noisy that limits choises.