In any way, really.
the Clef- family and Solosis, Duosion, and Reuniclus are the only Pokemon with Magic Guard and Endeavor, but none of them learn any damaging priority moves, sorry
Sources: Pokemon Showdown's teambuilder, https://pokemondb.net/pokedex/reuniclus, and https://pokemondb.net/pokedex/clefable
Clefable and Reuniclus both have Endeavor and Magic Guard, but they do not learn any priority moves.
Source: Showdown Teambuilder