Relikath, the Fallout Queen

Untapped Slivers you control have Decay
Sliver spells you cast have Cascade, Cascade
Whenever a sliver dies, flip a coin, if it lands heads, seek a sliver card and up it on the battlefield, with "This creature is unaffected by Decay".
{3}: Seek a sliver card, and put it on the battlefield face down, it has Morph X, where
X is its mana value.