How do you play
Demonic Pact on your opponent?
You're mana curve is too steep for legacy. If
Sanguine Bond and
Exquisite Blood are the core combo of your deck, they should both be at 4.
Nevinyrral's Disk isn't needed; the game will end next time an ability resolves and the opponent has 0 life.
704.3. Whenever a player would get priority (see rule 116, “Timing and Priority”), the game checks for any of the listed conditions for state-based actions, then performs all applicable state-based actions simultaneously as a single event. If any state-based actions are performed as a result of a check, the check is repeated; otherwise all triggered abilities that are waiting to be put on the stack are put on the stack, then the check is repeated. Once no more state-based actions have been performed as the result of a check and no triggered abilities are waiting to be put on the stack, the appropriate player gets priority. This process also occurs during the cleanup step (see rule 514), except that if no statebased actions are performed as the result of the step’s first check and no triggered abilities are waiting to be put on the stack, then no player gets priority and the step
ends.
704.5. The state-based actions are as follows:
704.5a If a player has 0 or less life, he or she loses the game.
116.3b The active player receives priority after a spell or ability (other than a mana ability) resolves