Unclear wording has made me wonder whether I'm even right, but I activated Just Desserts chained to Ojama Trio in my main phase 1 dealng 2500 damage, and then attempted to activate Card of Demise but was only given the option to set. I had 33 cards in deck, opponent had one set spell/trap and two set monsters, Card of demise was not part of the chain and I hadn't activated a Card of Demise yet that turn. My only guess is that the damage dealt prevented activation despite the wording specifying that the opponent takes no damage for the rest of this turn AFTER this card resolves. Any ideas?
You cannot Special Summon during the turn you activated card of demise, so if you already special summoned a monster, you cant activate card of demise in the same turn, in this case you already special summoned monsters by effect of Ojama Trio (even if its summoned to your opponent's field, its still your card so it counts as you special summoning)