Brave roy had fury 3 and neutral attack and speed. Gunnthrá is a +1 merge and has +atk but as long as she outspeeds the red and blue mages with aid from her blizzard tome she should live. Camus and B.Lyn dont really do much except have hone cav and reposition.
Start up by putting roy in the bottle neck with a hone cav behind him and Gunnthrá one space north of the hone cav. Next turn have roy kill the axe unit next to robin and pull him back to the bottleneck and end the turn. Next have Gunnthrá kill the axe unit that moved up and move the hone cav north of her. Move roy three spaces south of gunnthrá and the other hone cav one spot south of roy. Next turn gunnthrá kills the lance unit and is repositioned north so roy can be repositioned north and can defeat robin.

Fate Grand Order
Dragonball Legends
IV Calc
Heroes