Lucas, the Volatile Scholar

Lucas cannot be a creature unless your devotion to blue and green is five or more.
Time-Bomb 3. (For the next three end steps after entering the battlefield as a creature, Lucas gets three +1/+1 counters. After these sacrifice Lucas.)
{6}, Sacrifice another Legendary Creature: Destroy all other creatures, enchantments, and artifacts.
-Fateful Hour 5. If you have five or less health and use the above ability, win the game instead.