The utility cards can be earned in-game, playing the PvE on the Elementals Dungeon or in the airdrop events. There are 3 types of Elemental Utility Cards: the Fusion Cards, Evolution Cards, and the Summon Cards. The Fusion Cards and Evolution Cards have a rarity level and the Summons Cards have not. Below there are the rates and rarity levels that can drop in the dungeon floors.
Percentage drop rate for each utility card on each dungeon Floor.
Percentage drop rate for each rarity fusion cards
Percentage drop rate for each evolution card by level.
Percentage drop rate for summon cards by floor.