Tactics for Conflux.

Could you please advise on this topic? Is it worth getting the Water Mastery skill? It seems that with Conflux's large damage range among its units, the Blessing skill would be very useful, but the following thoughts arise. Given that I already have Air and Earth Mastery with Haste and Slow, and considering that I might also be slowed down, the question is: how many turns will the Blessing be delayed in a crucial battle? I'm wondering if it will even come to using Water magic. Perhaps it's not worth taking it after all? Of course, there's Prayer, but it's not always available.