To calculate this myself I used this hypergeometric calculator
Lower the draw bridge." At Pro TourHollywood I was beating up on a Merfolk deck whose creatures were far too puny to dare stand in my way
If you are jamming a few Eldrazi Titans and don't want to wait ten turns to cast them, you can power them out on turn six or so with the right ramp package
Underrealm Lich Self-mill is generally the first step in your gameplan, so its very impressive that a five-drop made it this high on the list
Making changelings is also a big deal, letting you use this as a synergy card for some lesser typal decks like spiders, minotaurs, and so on
Of course, the heroic ability is mostly just flavor text in constructed, but it did become relevant every once in a while