Right now sucks so badly, what the matter in having 3 or more clones if any enemy will target Killjoy and kill him like paper and clones PLOP! The enemies keep ignoring the clones and focus on Killjoy, they never kill the clones, they just kill JOY, the idea on paper is good, you must kill the clones to reach the master but the game is not working like that.
So:

1. Make Killjoy untargetable until all the clones are destroyed.
or
2. Make clones remain despite killjoy dies (he will surely do)

Just noticed another thing that sucks about this ultimate, when you make a clone, you clone the enemy with the current life, so its the enemy is about to die so it's the clone, clones should appears with full life, because they are only cannon fodder that doesn't do any damage but basic attack, if they were like aqua clones that can ultimate you few seconds after summoning i could understand this, but what the meaning of a cannon fodder without life?
FIX this NOW!