Davos, the Glyphweaver

If there are no concentration counters on Davos,
the Glyphweaver, you may exile an instant or sorcery in your graveyard and put concentration counters equal to its mana value on Davos, the Glyphweaver. If there are no concentration counters on Davos, the Glyphweaver, you
may cast cards exiled this way without paying their mana cost. If cards cast this way would go to your graveyard, they are exiled instead.

During your upkeep, you may remove a concentration counter from Davos, the Glyphweaver.