If a monster(s) is Normal or Special Summoned to your opponent's field, while this card is in your Monster Zone (except during the Damage Step): You can Fusion Summon 1 "GMX" Fusion Monster from your Extra Deck, by shuffling its materials from your field, GY, and/or banishment into the Deck
Its other abilities will tell you how it benefits the equipped creature, and it can be attached to other creatures you control using its equip ability.
However, considering how small the values are, these massive percentage shifts aren't likely to mean that this card will rise anytime soon
Anytime Gwaihir attacks you can give another attacking creature flying for the turn
Walmart: Paid Walmart+ members can access preorders from 7 AM PT / 10 AM ET on October 9 TCGplayer : The only place with standard Phantasmal Flames ETB stock readily available
Everything Ive already mentioned gives you a base for how to make your own proxies or where to get them, but making a cube means youre going to need proxies in bulk