When Glacial Pool enters the battlefield, sacrifice it unless you pay .
: Add or to your mana pool.
: Add to your mana pool. Put Glacial Pool on top of your library.
When Glacial Pool enters the battlefield, put a -1/-1 counter on target land.
.
: Add or 
to your mana pool.: Add 
to your mana pool. Put Glacial Pool on top of your library.
