So the “mechanics” it’s not taken from the game but it’s a nested array pulled out from the text field. Ok.

Arcane Missiles has the mechanic “ImmuneToSpellpower” in-game because when it is empowered by spell power it doesn’t shoot three 2 damage missiles but instead shoots one extra missile.

Currently the API mostly lists the bold keywords seen on cards as “mechanics” with the addition of some others that aren’t actual keywords, such as “ImmuneToSpellpower”, “AIMustPlay” etc. I’ve added “Can’t be targeted” to the list of potentially being added to the mechanics data in the future.

Hope that clears up some confusion.