[Verjigorm]

It's probably border spread if your aerial patrols can't get rid of it. Remember, it's a lot harder to get rid of large numbers black candles with preaching.

After you cleanse your land of your opponent's dominion, you should position your skeptics on territories where your opponent has temples or near them. This will mute the spread of his dominion. A skeptic has a 90% chance of nullifying a point of dominion minus 5% per enemy candle, so in a 5 red candle province, a skeptic still has a 65% chance of nullifying a candle each turn.

You can't really stop blood sacrifice dominion spread easily if he's using it extensively because each sacrifice counts as a temple check, so if he's burning 10 slaves a turn, that's like having 10 temples in that province which means that you would need about 11 skeptics in that province or in the general vicinity to squelch his sacrifice provided the provinces your skeptics occupy have 0-1ish dominion.

If you surround a temple with skeptics, you can nullify it's power in a similar manner to sitting on the temple itself. This is good in cases where, for instance, he has 10 dominion on the temple square (where your skeptics will have only a 40% chance to nullify a candle), and only 3 dominion in surrounding provinces where you'll have a 75% chance to nullify.

Essentially, position your skeptics inside enemy dominion where the enemy dominion is the weakest to exact the greatest loss of candles.

Remember that a temple boosts the power of your preaching, too, by 1 level.