(Keldon Cradle isn't a spell.)
Keldon Cradle enters the battlefield tapped unless you reveal a Green card from your hand.
, : Look at target player's hand.
: Add or to your mana pool.
Sacrifice Keldon Cradle: Add or to your mana pool.
, 
: Look at target player's hand.: Add 
or 
to your mana pool. or to your mana pool.
