Attempt to draw card, instead choosing to mill 5 cards and return Stinkweed Imp from your graveyard to your hand.
If you milled a nonland card, The Wise Mothman triggers, putting a +1/+1 counter on Benthic Biomancer.
Benthic Biomancer triggers, causing you to draw a card and discard Stinkweed Imp.
Repeat.

Infinite self-mill

Benthic Biomancer

The Wise Mothman

Stinkweed Imp

Activate Stinkweed Imp's cycling ability by paying {0} and discarding it, causing you to mill a number of cards and return Stinkweed Imp from your graveyard to your hand due to its dredge ability.
Repeat.

Rhet-Tomb Mystic

New Perspectives

Put a +1/+1 counter on Benthic Biomancer.
Benthic Biomancer triggers, causing you to mill five cards and return Stinkweed Imp from your graveyard to your hand, and then causing you to discard Stinkweed Imp.
Thran Vigil triggers, putting a +1/+1 counter on Benthic Biomancer.
Repeat from step 2.

Thran Vigil

Cast Stinkweed Imp by paying {B} due to The Sibsig Ceremony.
When Stinkweed Imp enters, The Sibsig Ceremony and Kindred Discovery trigger.
Holding priority, activate Phyrexian Altar by sacrificing Stinkweed Imp, adding {B}.
Resolve the Sibsig Ceremony trigger, failing to destroy Stinkweed Imp as it's no longer on the battlefield and creating a 2/2 Zombie Druid creature token.
Resolve the Kindred Discovery trigger, causing you to mill five cards and return Stinkweed Imp from your graveyard to your hand due to Stinkweed Imp's dredge ability.
Repeat.

Combos with "Stinkweed Imp"