Many players have been waiting for a way to counter the effect of Winota, Joiner of Forces. Containment Priest does exactly that, sending all creatures that would enter the battlefield from Winota's triggered ability into exile.
Unfortunately, the Escape mechanic is still considered a cast mechanic, so that one won't work, but every other effect will, including the dreaded Cauldron Familiar and Witch's Oven combo.
Discontinuity also prevents effects from Lukka, Coppercoat Outcast and Transmogrify. So, if you've grown weary of all these combos, then consider Containment Priest for your sideboard.