It's not strictly necessary, but it is helpful in a lot of decks
Grade: Sideboard Rimeshield Frost Giant A likely target of Fly, though Im not sure who was sitting around saying, Cold-Water Snapper
While it has its strengths, there are potentially better cards like Gem-Knight Lazuli, which offers more consistent recursion, or Gem-Knight Seraphinite, which provides additional Normal Summons
Now, whenever Six swings you can mill three and reload a land to your hand for more leaves the graveyard triggers
Both of them wreak havoc in casual/high power metas
Within each Pokmons section, you can sort by set release date, card type, or just whatever looks best