Serpent Generator - Legends (LEG){4}, {T}: Create a 1 1 colorless Snake artifact creature token. It has "Whenever this creature deals damage to a player, that player gets a poison counter." (A player with ten or more poison counters loses the game.)

return that creature to its owner's hand at end of combat

gain control of target creature that player controls with power less than or equal to the tapped creature's power for as long as you control Nihiloor

exile another target permanent

Begin the hymns

Put a +1/+1 counter or a loyalty counter on it

It is a terrifying power

Some teach

When Uro enters the battlefield

and a shield counter on it

) When Raven Familiar enters the battlefield

Pay 4 life: Underrealm Lich gains indestructible until end of turn

) Exile all nonland permanents that aren't legendary