Aside from a few cards here and there, the main difference between competitive Pioneer and competitive Explorer is that you cant play the Lotus Field combo deck in Explorer
Its unorthodox, but a great way to showcase this incredible art
In fact, I don't even think that this one is necessarily the best
Entomb and the fixed version of it, Unmarked Grave, are far more flexible, allowing you to set up spells with flashback like Past in Flames, additional static benefits through cards like Riftstone Portal, or simply open up more targets for you to recover through an Eternal Witness
It features in Jean-Emmanuel Deprazs 2018 World Magic Cup Winning Golgari Aggro list, and has since enjoyed something of a resurgence in Modern thanks to the Amalia Benavides Aguirre Amalia Life deck and the Abzan Chords of Calling Chord Toolbox variant