Paying life is around in the format but it isnt some huge theme, and you need to both pay life and have a card where it matters that you can reduce its cost It can ramp your mana quite effectively, and that makes it more likely that you can get a creature with power 4 or great into play quickly, at which point Ruby herself becomes a significantly better attacker
The deck then adds a number of powerful artifacts and vehicles including The Belligerent (creates treasures/draw), Magmatic Galleon (powerful removal/strong vehicle), Dire Flail (buff pirate/craft with artifact), etc
Ive rounded up the best ones worth your time smart, addictive, and built to keep your brain firing
If you go this route, you should also begin with a Mewtwo pack to obtain one Marowak EX for free
One instance is Hisuian Zoroark VSTAR [Lost Origin]this card is absolutely a powerhouse
All in all, there arent many decks that can match the power level of the Charizard ex deck, so expect to see it a lot at EUIC