Aloros, Righteous Exemplar

Whenever one or more knights you control with
no generic mana symbols in their mana costs
deals combat damage, you may draw a card and
put a shield counter on another creature you
control.
{w}{r/w}{w/b}, remove 3 shield counters from creatures
you control: Creatures you control gain +3/+3
and trample until end of turn. You may activate
this ability only once per turn.