As much as I love using it, Strands of Power should probably be a tier 3 spell instead of tier 2. I believe the mana cost and upkeep are fair for what it does, but it can have a seriously grand effect on the early game. Just picture a city with 7 terrain types. That gives the player +7 power for a 2 mana upkeep only 10 turns into the game. If they have another city by then, 5 turns later they could get another +7 power. Late game, that is not a huge deal, but in early game it's very powerful.