Ximrod, Machinator Menace

Ximrod enters the battlefield with X +1/+1 counters on it. Artifact spells you control with converted mana cost equal to or less than
Ximrod's power can't be countered.
Whenever a creature or artifact you control is
sent to your graveyard from the battlefield, you may return from your graveyard to your hand another target artifact card with converted mana cost equal to or less than Ximrod's power.