In the challenges, you battle your way through games against each of the five colors of MTG
Darksteel was the first "small" expansion to have 165 cards, where as previous small expansions had 143, (with the exception of Legions which had 145 as a balance among the five colors.) The following mechanics first appeared in Darksteel: Indestructible - Mechanic that made permanents indestructible
Like many of this style of one-word names, they adhere to a joke or reference, and reprinting them limits the novelty, and if we ever get a Sesame Street crossover, they might regret using Six if they introduce a cycle of Count-ing cards
Sidequest: Raise a Chocobo / Black Chocobo Sidequest: Raise a Chocobo starts as a modest enchantment that makes a Bird
Ultimately, Immerwolf could see play in a focused tribal deck aiming to overwhelm opponents with a pack of fierce creatures