Be'lakor, the Dark MasterBe'lakor, the Dark Master, Heralds of TzeentchHeralds of Tzeentch, and Lord of ChangeLord of Change are all perfect examples of that
When a card or archetype becomes dominant, the metagame will change relatively slowly, and it may take a ban or an impactful set to shake things up
Common features a circle, with one edge around it and a dull, gray color
Perfect for Commander Decks With 100 sleeves per pack, you can protect an entire Commander deck without needing extra packs
Thankfully, over the years Wizards of the Coast has made Hydras that rise above being just big and dumb, enough that building a tribal deck around Hydras has become a consideration, especially once they printed Unbound Flourishing
Its good to know that two of the premier sources of unblockable are nice and cheap