Kazuki, The Lonely

Shroud
When this creature attacks alone, it gets, +2/-3, Doublestrike, Indestructible, Lifelink, and Fear.
When this creature attacks with one or more creatures, it gets -3/+2 , Deathtouch, Firststrike,
and "When this creature deals damage to a player,
they lose the game unless they discard 5 cards,
lose 10 life, and sacrifice 5 permanents."
"All the people I knew... Taken by the evil monster...
Sharad."