Blackblade Reforged is a bit unwieldy if your deck doesn't have a high enough density of legendary creatures, but if you do it makes sure your creatures grow huge
That makes it a great commander option, able to use lots of powerful cards that wouldn't normally find their way into EDH decks
If you can spend seven mana on this creature, you can even replace it, which makes the card strict card advantage alongside its other benefits
Yes, hexproof-granting effects like Tamiyo's SafekeepingTamiyo's Safekeeping and other weird cards like Teferi's ProtectionTeferi's Protection get around it, but it's great to be able to simply ignore a lot of what blue decks can do to protect their crucial permanents
Theres the modality aspect, too, and it gets around indestructible lands
A note about Sacrifice MTG Sacrifice is a keyword action that puts a permanent you control into its owners graveyard