Beckett, Anxious Guardian

Whenever a creature enters the battlefield under an opponent's control you may pay,
{2}{b}: Put a -1/-1 on target creature that entered the battlefield under opponents' control this turn. {2}{g}: This creature gets +1/+1 and fights target creature that entered the battlefield under opponents' control this turn. {2}{r}: Each other creature under your control gains mentor and +1/+0 until end of turn. {2}{r}: Gain 1 life for each Cat or Human under your control.
"An admirable annoyance."