When Howltooth Castle enters the battlefield, sacrifice it unless you pay .
: Add or to your mana pool.
: Add to your mana pool. Put Howltooth Castle on top of your library.
: Return Howltooth Castle to its owner's hand.
.
: Add or 
to your mana pool.: Add 
to your mana pool. Put Howltooth Castle on top of your library.: Return Howltooth Castle to its owner's hand.
