Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a Dog you control may become lethal if Pack Leader leaves the battlefield during that turn.
23-06-2020
wotc
Once Pack Leader attacks, its effect prevents damage that would be dealt to Dogs you control even if Pack Leader leaves the battlefield.
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.