Based on my own experience with opening this set, here's the pull rates for Mega Evolution: Double Rares (ex): 21.8% or 1 in 4.6 packs Ultra Rares: 10.9% or 1 in 9.2 packs Illustration Rares: 10.9% or 1 in 9.2 packs Special Illustration Rares and Holo Rares: At least 1 in over 55 packs With that being said, here's some of the best cards I've pulled from Mega Evolution and where you can get them right now: Should you get Pokmon TCG: Mega Evolution
Log in RULINGS 2024-07-26 If the cost to cast a spell is increased, decreased, or changed because of additional or alternative costs, expend counts only the mana you actually spent
In fact you dont even need to use Polymerization
Other than that, the devs frequently drop free Pack Hourglasses inside the in-game mailbox
It is also worth mentioning that this card is now legal in the Modern format
XY-Dragon Cannon X LIGHT Level 6 [ Machine / FusionEffect ] ATK 2200 DEF 1900 "X-Head Cannon" + "Y-Dragon Head" Must first be Special Summoned (from your Extra Deck) by banishing the above cards you control