Let's say I was at 5, I had two Tryndamere, I assigned 5 damage, and my opponent had control of another battlefield with 2 Sprites. Do I win when I conquer since I go from 5 to 8?

Ruling: You win the game

Yes, you win the game. You reach 8 points through your actions, satisfying the victory requirements.

Sequence of Events

When you conquer the battlefield, the following events occur in order:

1. Standard Conquer Point: You gain 1 point for the standard Conquer action. Since you were at 5 points, you are now at 6 points.
   • Note: Per Rule 466.1.b.2, the requirement to have scored every battlefield this turn only applies if you are at 7 points or higher. Since you are at 5 points (and then 6), this restriction does not apply.
2. Tryndamere Trigger (First): Assuming both Tryndameres were part of the attacking force and the conditions for "5 or more excess damage" were met, the first ability triggers.
   • As established in RiftJudge FAQ #63, this ability scores an additional point.
   • You go from 6 points to 7 points.
3. Tryndamere Trigger (Second): The second Tryndamere's ability triggers.
   • You go from 7 points to 8 points.

Victory Conditions

According to Rule 323.1 and Rule 467, you win the game if you have 8 or more points and more points than any opponent.

• Bypassing the Conquer restriction: Per RiftJudge FAQ #63 and Rule 466.1.a.1, the "score all battlefields" restriction applies to the Conquer point itself, but not to additional victory points gained from triggered abilities. Because these points are not gained directly from the Conquer action, they are not beholden to these restrictions.

Since you reach 8 points and your opponent does not have more points than you, the game ends, and you win.

Note: I could not fully verify this ruling against the retrieved rules, specifically regarding the distinction between total damage assigned and "excess" damage as defined in FAQ #8955.