Similar to how we have on-escape moves, perhaps we should have on swap-in moves. One of these could be given to Mortem Rex. It could be something similar to Primal Brace. It would give Mortem shields and an attack buff so it can better counter creatures like Ceramagnus. Or perhaps we could have a move that does a rally heal on a swap-in. These moves would always act before the moves of the swapper.