Skill synergies.

I would like to know your opinion on ability combinations for archers, mages, and any units. The crazier the combination, the better, but we shouldn't forget about balance and playability. For example, I had the idea to make a summoner mage for either the Dwarves or the Sylvan faction. One could cast something like a wall of swords, traps, crystals, or a swarm – something defensive. And the attacking one could summon something like elementals or a weak phoenix, like one phoenix or several elementals, or maybe a phantom + channel.