I am very close to the end of the game now - level 28 and in the final land, and I am spamming Phantom every turn. Works very well with Knights (130 cap), I have found. Knight runs into the middle of the map, casts Phantom (about 50) which charge straight into the enemy. On Turn 1, the AI will pretty much swarm this unit which gives you time for ragebox/ranged units. Turn 2, out pops another 50 Knights.
