Ada, Blacksmiths Prodigy

Equipment spells cost {1} less to cost
If you control 4 or more Equipment, other
creatures gain +0/+1
When a Knight is destroyed, deal 1 damage to
target creature
{1}{r}{r}: Equipped creatures gain +1/+1 until end
of turn
{1}{r}{r}{t}: Create a +0/+1 Knight token with
defender which is also an Equipment
{3}{r}{r}{t}: Untap target non-land
permanent you control