Although this card is an enchantment, due to the requirement to sacrifice it at the end of your step, it actually works like a spell. But even then it's a very strong spell. It allows you to bring a good number of cards back from your graveyard in one turn. The only condition is that you already have enough mana and other cards in your graveyard to exile and pay for the Escape mechanic.
Underworld Breach can easily fit in any Storm or graveyard-based deck that is legal in the Pioneer format.