Markov Purifier's ability triggers if you gained any amount of life that turn, even if you also lost that much or more life
This also means that if you control Teysa and cast a second one, an ability that triggers when it dies due to the "legend rule" triggers three times
Making a player lose three life for every land played adds up quickly, and the counters let Ob Nixilis deal the last points of damage itself
Oko, Thief of Crowns Oko, Thief of Crowns is a stupidly broken yet deceptive planeswalker, which is quite fitting for the whole fairytale aesthetic that Throne of Eldraine had going on
But there is one card type that is core to what makes it work, and those are land cards
Dark Is Evil: Number XX: Utopic Dark Infinity is a DARK monster, and one of the flagship monsters of the ARC-V manga's Big Bad