The Creature chosen for the artwork simply showcases how powerful of a card this is and the design choice of a clearly angelic character possessed by a violet dark magic is evident
Krark, the Thumbless Krark, the Thumbless has certainly risen to the occasion when it comes to strong cEDH commanders
Instead, it's the fact that it allows the player to draw two cards when an equipped creature dies that pushes it over the top The potential card advantage is unreasonable for a single mana investment, especially since the -1 to Toughness makes it extremely easy for the player to kill their own creatures on command
It's like kicker, but from the graveyard
She's a mere 4/4, but she's also got a rather powerful mind-control effect, temporarily resurrecting a creature she personally slew, and having that creature fight for you as long as she's around
The rest of the equipment you need in your collection all happen to cost just a single mana