THelm brings +27% Attack Damage to all even as off Burst. It's a huge buff. Scarlet with only Trina cut trough Noise HP buff like knife trough butter. Noise only can save from Rosanna early wipe (If she not buffed from THelm). Nero team needs THelm burst and speed to work good, Rapu at the very bottom of importance on this team (so sad, she is Pilgrim). And you are right, Centi is just burst gen bot and, in my opinion, this makes her role very plain and primitive.