alright it is now cumulative, but just note that you could really easily make a single orb do 24 damage in one turn if you are lucky and opponent has a field full of say malignant cells. And then if you had more then one you could do lots of damage, it makes for a good combo decks ideas
as for why it creates feedbacks, umm its a magical orb, yeah thats it (I don't know orbs are always supposed to have magical effects)