Deathly Watchtower enters the battlefield tapped.
: Add or to your mana pool.
Put Deathly Watchtower on top of your library: Add to your mana pool.
: Deathly Watchtower becomes a 2/2 white Knight creature until end of turn. It's still a land.
: Add 
or 
to your mana pool.
to your mana pool. 
: Deathly Watchtower becomes a 2/2 white Knight creature until end of turn. It's still a land.
