If matches were longer, I think it would have a lot of value. But with short matches or loop builds, it doesn't do a whole lot.
Play some matches and count have many turns you take, but don't count any from match 4 or whatnot. When I tested, my Kraken build was around 7 frequently. So if I somehow cast enchant turn 1, and don't cast the enchanted troop until my winning turn, I'd get 6 total mana from it.