Casting Fire Covenant and Bond of Agony for X=0 causes a GSR
Steps to reproduce:
1. Begin casting Fire Covenant, choosing not to select any target.
2. Pay the mana cost of Fire Covenant.
The game appears to hang, the prompt box prompts the user to pay one extra mana (whichever color was the last mana paid for Fire Covenant's mana cost). Performing any actions other than casting Fire Covenant again will result in a Game Server Reset. Casting Fire Covenant again will prompt the user to select any number of targets again.
Fire Covenant is cast and goes to the graveyard. The user loses no life.
Updated Report with full information.