If my opponent has Tianna Crownguard at one battlefield and I hold (but don't gain a point due to her ability), can I then move to kill Tianna and conquer the other battlefield to win the game?

Ruling: Yes. Tianna Crownguard prevents you from gaining points, but does not prevent the act of Scoring itself. When you attempt to Hold a battlefield, it is marked as "Scored" for the turn even if Tianna prevents the point gain. After killing Tianna, if you Conquer the other battlefield and reach 8 points, you win because you have Scored both battlefields this turn.

Sequence:

• At the start of your turn, you attempt to Hold the first battlefield. Tianna prevents the point gain, but the battlefield is still marked as "Scored."
• You kill Tianna Crownguard during combat.
• You Conquer the second battlefield, marking it as "Scored."
• Because you have Scored every battlefield this turn and reached 8 points, you gain the Winning Point and win immediately.

Nuances:

• Tianna prevents gaining points but not the Scoring process itself.
• Each battlefield can only be Scored once per turn, but Scoring without gaining a point still counts toward the final point requirement.