Gulrang & Tocsin

Question : What happens if my tokens are Defender during a tie-breaker?

Answer : In the Arena, Expeditions can't move forward nor backwards since there's only one Region. Any such effect becomes irrelevant. Therefore Defender isn't a drawback anymore.

Question : If a Character is both Gigantic and Defender, for example because I control both Atlas (Rare, Ordis version) and Gulrang & Tocsin, what happens?

Answer : "My Expedition", for a Gigantic Character, means "my Expeditions", plural.
Therefore a Defender, Gigantic Character would prevent both their Expeditions to move forward.