Big stompy fish!
A lot of Leviathans have really bad "enters the battlefield" abilities (sacrifice lands, give away your permanents, etc.), so I need to run a lot of Stifle effects here.
You'll see a lot of cards that try to get around these bad effects (Time Stop, Illusionary Mask, etc.)
Since I was already there doing the theme, and there's not quite enough Leviathans, I added in some other huge creatures with bad ETB abilities as well.
I also put in some mana cost 9 cards for Grozoth to find.
Click here for a text version of this decklist
Click here for my EDH Commander decks