The card lists Mewtwo at 70 HP with Barrier as a zero-cost move that reduces incoming damage, a mechanical nod to the psychic shielding ability that defines the character's combat style
There have been other sculpture illustrations, like those from Sachiko Adachi or Hizuki Misono (who only produced four cards, but there are utterly endearing all the same)
Currently, damage order is used whenever an attacking creature was blocked by more than one creature, however according to WotC, this iteration has become unintuitive, adds a fair bit of rules baggage, and losing it means more interesting decisions and less double-dipping if you know the tricks. The change to damage assignment order is as follows: What Happens During Standard Rotation
Part of this is also because, while a good series, the Fallout games only really took off after Fallout 3, meaning that half of the main games in the series are comparatively niche