Bombur, the Wide

Sacrifice an artifact token: Bombur gets +0/+2
until end of turn. If this is the third time this
ability has been activated this turn, Bombur also
gains double strike.
Brotherhood with Bifur, the Unhinged and
Bofur, the Bard (If you control either Bifur or
Bofur, then Bombur gets +1/+1, if you control both
then Bombur instead gets +2/+2; you may have
multiple commanders if they are all in a brotherhood.)