Note that Red does have some abilities, like Flaring Pain, that can let damage and kill something normally preventing its damage, as well as a few destruction abilities like Chaos Warp, Fissure, and Aftershock you may uncover
THIS IS ALSO IN NO WAY A GUARANTEE
On the flip side, I excluded commanders like Chulane, Teller of TalesChulane, Teller of Tales, because while they might be extremely strong Merfolk commanders, they don't support Merfolk more than any other type
Stay safe and have fun
Among existing Deaths Shadow decks, youd most want to play it in Jund Deaths Shadow so that you can return Tarmogoyf with your Deaths Shadow if you cast this for X=2, but with the addition of Scourge of the Skyclaves as an additional Deaths Shadow, we might be able to have a strong two-mana creature to return in any color combination
Earthquake is an incredibly fast attack with amazing value