If you would scry a number of cards, scry that many cards plus one instead.
: Look at the top card of your library. If it's a Kraken, Leviathan, Octopus, or Serpent creature card, you may put it onto the battlefield. If you don't put the card onto the battlefield, you may put it on the bottom of your library.
Kenessos is a sea-monster cheat engine: tap out for the ability to dig and slam Krakens, Leviathans, Octopuses, and Serpents straight onto the battlefield, paying nothing for their massive mana costs. You ramp and stock your library with huge fatties, use scry/topdeck manipulation (buffed by his +1 scry) to line up hits, then overwhelm the table with giant bodies. Win by smashing in with monsters or by leveraging their cast/ETB triggers.
Cheats enormous, normally-uncastable beaters into play for a fixed cost regardless of their mana value
Repeatable activated ability that grinds card advantage and board presence every turn
Scry-plus-one passive sharpens every scry effect and pairs with topdeck tutors to guarantee hits
Green-blue gives access to elite ramp, card draw, and counterspell protection
Activated ability only puts the card in if it's the TOP card—whiffs without library manipulation
Sea monsters tend to be slow, expensive to hard-cast, and easy to remove for value
Heavily reliant on the commander; if Kenessos is removed repeatedly the engine stalls
Limited interaction and few fast combo lines—vulnerable to faster decks and board wipes
A parallel cheat engine that drops the same monster pool into play, doubling your free fatties.
Add top-of-library control—Sensei's Divining Top, Sylvan Library, Mystic Sanctuary, Brainstorm—so the activated ability never whiffs. Include untappers and flicker (Thassa, Deep-Dwelling; Seedborn Muse; Ghostly Flicker) to fire the ability multiple times per turn, plus protection like Heroic Intervention and counters to defend your engine. Trim weaker vanilla monsters for ones with relevant ETBs or evasion so each cheat advances a real game plan.
Legendary Creature — Merfolk Cleric
: Look at the top card of your library. If it's a Kraken, Leviathan, Octopus, or Serpent creature card, you may put it onto the battlefield. If you don't put the card onto the battlefield, you may put it on the bottom of your library.