Dainsleif

Equipped creature gets +2/+1 and has to attack
each turn if able, if equipped creature can't
attack put a -1/-1 counter on it
If equipped creature doesn't kill its assigned attacking or blocking creature the controller of equipped creature loses 1 life
Once Dainsleif is unsheathed it must kill someone
before it can be sheathed once again, and every hit
will either kill its target or leave a severe and
permanent wound