You can only use this effect of "Gouki Octostretch" once per turn
One of the biggest weaknesses in a mono black MTG deck is black enchantment removal spells
Some major Sea Serpent-Type monsters include "Levia-Dragon - Daedalus", "Ocean Dragon Lord - Neo-Daedalus", "Orca Mega-Fortress of Darkness", "Bahamut Shark", "Brionac, Dragon of the Ice Barrier", "Sea Dragon Lord Gishilnodon", "Lavalval Chain", "Water Dragon", "Deep Sea Diva", "Moulinglacia the Elemental Lord", "Number 32: Shark Drake", "Abyss Dweller", "Mermail Abyssmegalo", and "Poseidra, the Atlantean Dragon"
Creatures (10) Planeswalkers (6) Lands (23) Spells (21) There are a lot of small interactions in the deck I really like
To clarify, Second Coin Toss doesn't allow its user to redo the flip for Lucky Chance, so it's best to choose the optimal flip for that card the first time around
Oddly enough, you get 2 copies of Salamangreat Heatleo, meaning you'll end up with 6 total copies that you can't dismantle if you get 3 decks