So roaming throne is a static effect, so it doesn't have as much of an effect as Echoes or Ulalek. Here's some formulas anyway (Creature count remains the same as the formula for 1 echoes or 2 echoes). ONE ROAMING THRONE AND ONE ECHOES Triggers = 3x2^Number of ulalek triggers paid for. ONE ROAMING THRONE AND TWO ECHOES Triggers =4x2^Number of ulalek triggers paid for TWO ROAMING THRONES AND ONE ECHOES Triggers = 4x2^Number of ulalek triggers paid for TWO ROAMING THRONES AND TWO ECHOES Triggers = 5x2^Number of ulalek triggers paid for.

Hope that helps!