Apparently rosette patterns are good to look for, which this Charizard seems to have
To truly pull this combo off, you need to be sure you can attack with your Xyz-summoned monster during the battle phase, so having a Lightning Storm spell to hand would be useful
It can generate mana, and if you're not using it for mana, can tap it to draw a card instead
This is especially popular for powered cubes, vintage cubes, dual lands, reserve list staples, and highly optimized Commander environments where replacement costs can become extremely high
4 Bushwhack Thin Your Deck Or Fight A Creature Another modal fight spell, this card allows you to either thin your deck of basic lands, which is always useful, especially in the early game, or trigger a fight between a creature of yours and your opponents
Everything I said about Mudfire goes double here