As you may already know, Holo cards have been among the most desirable variants since the Base Set (1999)
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a flashback cost), add any cost increases (such as kicker costs), then apply any cost reductions (such as that of The Earth Crystal's first ability)
In other words, your deck will need to contain cards with the H, I, J, and any other mark that is printed afterwards (yes, they go in alphabetical order, as you see)
(9/20/2024) A permanent that turns face up or face down changes characteristics but is otherwise the same permanent
A card like Tifa, Martial Artist gives you 1 extra combat for each opponent youve managed to hit, so its a slightly different rule