You and Ooze Army? (UG04a) [Unknown Event]

Amass Oozes X, where X is the number of creature types among creatures on the battlefield. Don't count changelings. That would be ridiculous. (To amass Oozes X, put X +1/+1 counters on an Army you control. It's also an Ooze. If you don't control an Army, create a 0/0 black Ooze Army creature token first.)