There are countless dragons of great strength in Magic, many of which are legendary, allowing them to potentially be used as the centerpiece of one's Commander deck
You pay all costs and follow all normal timing rules for the card played from exile with a Junk token's ability
Furthermore, Darkness Claw requires just two Energy and Mega Absol ex is a Basic card (no evolution required), so it can be on the field from the very start of the game and make an impact almost immediately
The exception is auras that specifically enchant a permanent you control. For example, Cartouche of Knowledge has enchant creature you control. If you take control of a creature with this Cartouche on it, it falls off since your opponent still controls the aura but no longer controls the enchanted creature
Certain actions can also manipulate the job gauge, removing the item's Condition state entirely
Slows the game down, especially if youre one of the last two