Fen's Staff of Healing

{p/g}{p/g}{p/c}{p/c}: If a white or green dragon has been
sent to your graveyard take it out and put it on the battlefield, tapped. Put a 0/X counter on
the dragon (X is equal to the number
of turns the dragon survives after being brought back from the graveyard)
All monocolored green creatures with toughness 4 and below have trample