You do not want to duel Maeve as her combo WILL one shot you. Stay away from where she likes to play unless you have an ally who can kill Maeve first with you.
If you have pounce available don't be afraid to engage Talus. Hitting both daggers, pouncing and hiting both daggers again will finish off Talus before he can react.
If Meave isn't using Artful Dodger, and you have Surprise Attack, break hidden with Poison Bolts and do your hit her once from behind. Follow that up by using smoke screen to hide yourself and let the damage encourage Maeve to retreat.
Careful near edges as cassie can one shot you if she sends you out of the map. knowing this she may chase you there in order to get an easy kill. Try knocking her off instead or leading her to a team member who can if you need to retreat.
Cassie's Roll'n'Shoot combo givers her shot 195 bonus damage a shot if she can consistently hit you. and it reduces her roll's cooldown to 1s. If she rolls, try using a movement ability to make her miss out on the extra damage have to wait full time.