Best card in legacy and modern.
I know that's a blanket statement, but I'm honestly serious. Griselbrand is currently the backbone to one of the very, very few modern decks that can win on turn 3 in Grixis Vengeance/Through the Breach. And is a powerhouse in legacy, being the win con for Reanimator and the engine for Tin Fins, or whatever name people are using for it now.
Such a fantastic card, just wish he had a home in standard. My 2 copies of the card have gained 50% value since I bought them a few months ago too, so people are definitely seeing the potency in non-rotating formats.