Opposition Agent was created as a way to combat the tutor-heavy decks, which is what cEDH decks usually do to win
Reviews can usually give you this info, as sleeves with awful durability will probably get absolutely blasted
His ability is a strong support for the rest of the deck and its play style no matter if Wulfgar is played as commander or regular creature because every triggered Ability of a permanent, which is triggered by attacking creatures, is effected another time
Expect to see plenty of Vraskas Contempt in every black midrange deck as well, and most likely even aggressive builds with Ruin Raider
This area really helps your deck burn bright
For example, if you control Muldrotha, the Gravetide ("During each of your turns, you may play a land and cast a permanent spell of each permanent type from your graveyard") and you cast a creature spell from your graveyard during your second main phase, you won't be able to cast another creature spell from your graveyard with Muldrotha's permission until after your next ending phase ends