I've tried this post three times, so lets see if it works this time . . .
Another thought for an action in this fight or later: you can "hold an action." The idea is that you say, "I want to do this specific thing, but I'm going to wait until this other thing happens." For example, you could ready an attack (or two if you get them)but not attack at you rnormal initiative. Instead you wait until an imp reappears and then attack. the reappearance of an imp is the stated trigger. Doing this allows you to time your attack with other events and react to things tht would normally happen after your turn in the initiative sequence. (Say, you go first and there is no imp to attack, but later in the round the imp reappears.) The downside is that if your trigger never happens (For example, an imp reappearing was the trigger an no imp reappears) then you have wasted your turn and do nothing.
Actually, this is a 5E rule. Not sure how it plays here..