sliver mtg commander deck Tutor - Sliver Overlord - 98 nonfoil cards) Sliver Hivelord Sliver Tribal Magic

This is direct from Wizards store and could mean that this is one of the cheapest prices you will find them online for

That's something to fear

Granted, its more restricted compared to the New Phyrexia artifact, but does see play in Commander

The true potential is unlocked upon transformation, where it morphs into a potent mana rock that can add a substantial amount of colored mana to your pool each turn based on the number of permanent cards in your graveyard

A key recursion piece in the Ur-Dragon, Scion of the Ur-Dragon and potentially the new Bladewing deck, Rivaz is still a solid creature

Your opponent, playing an aggro deck, is more or less spent