Have a bunch of stuff for Mono Blue Devotion, looking for some things to finish my mono black devotion and esper.

Major haves for Mono U are:
4 x Master of Waves
3 x Thassa, God of the Sea
4 x Tidebinder Mage (1 foil)
4 x Bident of Thassa
all of the commons/uncommons for the deck

1 x Tropical Island Revised (light play)

Major Needs:
2 x Underworld Connections
2 x Desecration Demon
3 x Sphinx's Revelation
1 x Hallowed Fountain
1 x Elspeth, Sun's Champion

Also have other things for trade in other formats as well! The Tropical Island is only for trade for Modern/Legacy playables.