When Gulchdrinker Serpent enters, detain target permanent. (Until your next turn, that permanent can't attack or block and its activated abilities can't be activated.)
“There are no serpents in the Bearidge Lake. Anyone found guilty of saying otherwise will be jailed six months if they were not eaten.” — The Judges' Law
Put target creature on top of its owner's library. Quickdraw {2}{U}(When a creature you control blocks or becomes blocked, you may cast this spell for {2}{U}.)
“There was peace here before you, refugees. Elf, centaur, and monster lived alongside, if not with, each other. I wonder why that peace has gone?” —Chief Striking Dawn
When Howler Sellout enters, for each creature that died this turn, post a bounty on up to one target creature an opponent controls. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)
When Howler Sheriff enters, gain control of up to one target creature with a bounty counter on it until end of turn. Untap that creature. It gains haste until end of turn.
Injustice deals 4 damage to target creature. Post a bounty on up to one other target creature. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)
Play with the top card of your library revealed. You may cast creature spells from the top of your library. You may cast Centaur spells this way without paying their mana costs.
“Every bit of land's got something that'll scare of its investors. The trick is to find it first, and failing that, invent something even worse.” —Lexie Boggs, aether baron