She is clearly best used as player phase unit. If you want to tank with her you can only be a physical tank. Well, you can kinda be a mixed bulk tank with high investment… but that will mean giving up on part of what makes her so good in player phase, and other units will still perform that role much better, my advice is to give up trying to do that.
What I did with my cherche (+10 now):
- ATK IV
Bonfire instead of ignis
A - Death blow
B - Desperation 2 (3 is not needed for this build)
C - Threaten defense/Attack Smoke/Defense smoke/Savage blow/Goad fliers (if used in a flier team)
S - Brash assault
This build is great with 3 dancers with wings of mercy, you just have to find a way to get her below 50% HP and then she slaughters everything. I soloed Thrasir Abyssal map with this build.
If you find getting below 50% in AA is inconsistent you can also try fire boost as the seal and something else on the B slot, this way you should try to kill everything in 2 hits. Blues and greens should not be a problem when you have 70-80 attack with a breave weapon. Don’t forget to bring dancers!