Karthion, Selfless Knight

Vigilance, First Strike
if Karthion, Selfless Knight is blocking alone,
it blocks up to 3 creatures.
if Karthion, Selfless Knight is attacking alone,
it gains +3/+0 until end of turn.
When Karthion, Selfless Knight dies, exile it,
then return it to the battlefield transformed
under your control.