My Recommendation : I, like most players who have played with Mewperior for any given amount of time, believe that it is certainly a fast, powerful and unexpected deck, but not Tier 1
But I really love that Osgir can copy and duplicate the artifact in one activation, for the mana cost of the target artifact in the graveyard and exiling it
The deck then plahys a number of anthem effects (Elvish Archdruid and Dwynen) and buff spells/effects (Preposterous Proportions, Overrun, Viven's Ultimate) which will make this elf army enormously powerful and able to swing for absolutely massive damage
Lifegain prevention is, much like lifegain itself, exactly the sort of narrow yet highly valuable mode you want on your modal cards
Arceus Pokemon Coloring Page Arceus appears with radiant ring motifs and elegant lines
Depending on how good the deck runs, he might actually not need all 3, but I think 3 greatly speeds up the engine, especially when Rank 4s are made too easy.