In Pokmon cards, a reverse holo means that the shiny, reflective foil covers the background of the card, while the Pokmon artwork itself stays matte
D/D/D Abyss King Gilgameshs effect is good enough that players are actually running two copies of it in their Extra Deck despite its 'once per turn' clause
This is a gem in the right deck, and attaching effects to lands is super powerful
Your best bet is to give it first strike in some way so it cant just be chumped by any ol 2/2 your opponent has lying around
Add in value engines like Jeskai Ascendancy and Storm-Kiln Artist, and the deck can explode out of nowhere with massive turns packed with spells, triggers, and damage
5 Forcing tribal spells because they are tribal, or having tribal effects just because they are tribal is bad design unless you plan to lower the whole powerlevel obscenely