Help with timing

[TheHuntsman]

So if my friend has a big monster in his hand and the wand of dowsing. If he plays the monster knowing he's not going to win and decides to use his wand of dowsing to pull "The Magic Lamp". The rod goes off and he pulls the card and instantly lays it down on the monster. Do I as another player get to react within that time to lay down a wandering monster so that the magic lamp isn't as useful? or is it since he laid down the card first it automatically goes through? is there time between actions that we are guaranteed a chance to play? he keeps telling me that the first card plays goes through first but much of this game seems reactive in nature.

this discussion started because I read a moderator say that someone can play a lose a class card during using dowsing rod and pulling divine intervention. i thought that in reaction to him using the dowsing rod I could then use curse to make him lose his class or a level if the intervention would let him win. He states that the card since played first finalizes first.

thanks