The Chamber of Secrets

{t}: Add {c} to your mana pool. You lose 1 life.
{x}, {t}, where X is the number of discovery counters on The Chamber of Secrets: Put a discovery counter on The Chamber of Secrets, then put an X/X Eldrazi Horror creature token onto the battlefield, where X is the number of discovery counters on The Chamber of Secrets.
"There is always a risk of knowledg- AHHH!"
- Morio the Archaeologist's last words