Binding coil is easy to run unsynced even solo, except for the last turn which I think requires two people but is still easy. Second coil actually gives you a run for your money, especially turns 3 and 4. I think turn 3 has one mechanic which requires at least three players. I wouldn't want to try that synced with random players. I haven't tried final coil yet so can't comment on it. I wouldn't mind introducing rebalanced versions of all three, similar in difficulty to the newer normal raids.