You know exactly which one is missing.
Four different accessories themed after Elemental HEROes have been announced. They will all be released on September the 2nd, 2022.
Elemental HERO Game Mat
MSRP: $14.99 per game mat
Elemental HERO Card Case
MSRP: $4.99 per case
Elemental HERO Card Sleeves
MSRP: $3.99 per pack of 50 sleeves