If you don't control a black permanent immediately after Parasitic Strix enters the battlefield, its ability doesn't trigger. If you don't control one as the ability resolves, no player loses or gains life. It doesn't have to be the same black permanent both times, however.
07-08-2020
wotc
Parasitic Strix's ability triggers only once, no matter how many black permanents you control beyond the first.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.