Werewolf

Silver Vulnerability (This creature can be damaged by Silver), Werewolf (This creature cannot take combat damage and must attack each turn if able, if this creature kills a creature, this creature gains +1/+1 until the beginning of your next upkeep)
{1}{r}{b}: Bite (This creature fights target creature, if neither creature dies, then that creature gains +3/+2, Werewolf, Silver Vulnerability, {1}{r}{b}: Bite, and becomes a black/red Supernatural Werewolf