The Ur-Arachnid

Eminence - As long as The Ur-Arachnid is in the
command zone or on the battlefield, other
spiders you control have reach and deathtouch.
{t}: Other creatures you control become 5/5
Black spider horrors until end of turn.
{3}: Tap target permanent, it does not untap
until The Ur-Arachnid leaves the battlefield.