It only costs one mana, and, for the cost of two mana and two life, players can activate Phyrexian Reclamation to return a creature from their graveyard to their hand
You get lifegain and card advantage based on the sacrificed creature's power, making it a versatile creature that can fit into many archetypes
However, this is a really risky card to play
It also means that if you really want access to these effects as a Commander player, you have a much more affordable route to getting a card with the same effect
Wild Mongrel is already a great creature, but when paired with double-strike effects like Double Cleave or Soul Fire, or madness cards like Basking Rootwalla or Reckless Wurm, it becomes one of the best cards in your deck
That's a bit of an exaggeration - there are likely to be cards in the deck that we want to keep, but I almost assuredly want to pair Eulogist with a Bant deck