You gain 2 life and scry 2 when you exile Senu, and when you hit with a legendary, probably your commander, you get to put Senu back into play attacking
Despite not being incredibly powerful, Slinn Voda, the Rising Deep is still one of the better cards in the Sea Monsters deck, and if you choose to build it as Mono Blue then Slinn is your best commander option
I wrote a whole lot about Land Tax in my Top 50 White Cards article, so I'm not going to go on and on about it here
Captain America can cheat around the equip cost of one Equipment per turn , but there are other cards in the deck to make it easy to equip Equipment without spending mana
Cycling ( , Discard this card: Draw a card.) Creature - Faerie Color tag templates(None) Cold-Eyed Selkie Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Whenever this creature deals combat damage to a player, you may draw that many cards