Supernatural Devourer is basically the best card you can give any Combat mystic at this point, it is honestly pretty undercosted itself.
As far as Lilith using all her AP to fight Ophiel, it really is a win/win for Samael. The rest of Empire is generally much easier to lock-down via status effects then Lilith (who can also buff other people), and Bless is one of the best buffs you can give an Empire team, with their typically low Attack/Defense scores.
If Ophiel has to mutually tie down a (slightly cheaper, but much better) leader, then it really should be to the Samael player's advantage.
In most situations, Ophiel and Lilith really wouldn't end up clashing unless we are at the tail-end of a game. Ophiel really should be off obliterating lesser characters, and Lilith is most likely playing support/ranged attacker unless you felt a pressing need for her to be in melee (like AoE clusters, or a high priority target has no AP).