Contested stronghold, overpowered ?

By kalle, in Warhammer: Invasion The Card Game

This card grants one power for every development on a given zone, so it's turned out to be really game winning card played on kingdom, more so if played early on. With empire or chaos, it seems hard to do anything for it. This one card makes the player controlling it able to build he's realm much more rapidly than other alternatives. So far, we've decided to house-rule it to only two developments, which is still enough for the price of the card.

Are we missing something, or is there a good counter strategy for this one ?