Ancient artifact of Tashnia

{t}: add {g} to your mana pool.
Whenever a creature attacks you or a planeswalker you control, Untap all creatures you control, those creatures get +1/+1 until end of turn.
It's name has since long been forgotten, the inscription has weathered away, It's mana is almost gone, But it's purpose still stands, to protect our people, to give us strength to prevail, to survive - Targa