Seraphina

{b}{u} - tap any creature you control to activate any and all actions that can or have already occurred on the board and use them in your favour
{b} - a creature under your control gets a permanent +1/+1 counter on it
{b}{b}{u}{u} - a creature under your control gets a permanent +3/+3 counter on it

'She swims alone, yet fights with an army'