Despite the fact that I like Joseph7's suggestion, I prefer to have as most as possible explicitly stated. While there are cards that stack and others that don't without having to state it on the card already in the game, I think this could also be one of those cases.
The question is, from a perspective of thematics, I would guess that having multiple Imp effects stack would make sense. Many troublemakers means lots of trouble. Having said that however, if 4 Imps were to convert the payment of a 4
Cockatrice, all the opponent would get would be the equivalent of a Nova.
We must consider certain factors however. Imp would devastate Mono decks the most, and as more elements are included in an opponent's deck, the effects are lessened and begin to turn into benefits for them. They can still deny cards however, and this is what is most powerful. One turn could be fatal.
Maybe the balancing factor should be to convert into a greater amount of random quanta. I wanted to turn 1 specific quanta into 3 random quanta because that seems to be the equivalence ratio when looking at Quantum Pillars and Elemental Pillars, however in this case maybe it is appropriate to change the ratio in favour of the random quanta?
What do you guys think?