Number 4: Numeron Gate Catvari

[ Machine / Xyz / Effect ] 3 Level 1 monsters Cannot be destroyed by battle. At the end of the Damage Step, if this card battled an opponent's monster: You can detach 1 material from this card; double the ATK of all "Numeron" monsters you currently control, until the end of this turn. ATK/ 1000 DEF/ 100