The set symbol is a small logo, a sword, a fist, a stylized letter, that identifies the expansion the card came from
Mega Brave was the first MEGA series expansion, alongside Mega Symphonia
While Wild Mongrel might be the primary engine for dropping an early Wurm, the best opening play possible for this deck would be first turn Careful Study, dropping two Basking Rootwallas into play
As well as Pikachu Illustrators extreme rarity, it is the only Pokmon card to be labelled as Illustrator in place of the standard Trainer text at the top of the card, with an accompanying pen icon in its bottom-right corner
As an artifact-centric commander, he certainly opens up a lot of different build paths from Equipment voltron to artifact combo
For the other two fossils, Regirock becomes a key component instead of Marshadow as it allows you to tank hits while you find your full Stage 2 line