If I recall correctly, you have to stifle the tokencreation-trigger before mana for it is payed. So if I have 15 mana available, a decree of justice and a mana drain, I can cycle decree (12 mana left), and then see if my opponent stifles the token-creation. If he doesnt, I can pump all my mana in the token-creation. If he does stifle, I can first mana drain his stifle, and thereafter create 10 tokens. Correct?
Correct