Stardock Under Siege (DDEP08-02) concludes with all of the tables in the Epic boarding skiffs and facing off against a massive mothership. The PCs are tasked with destroying the mothership before time runs out. At the end of each round, runners from each table report their table's damage total. The next round cannot start until damage has been reported. If the mothership reaches zero HP in time, it is successfully destroyed.
The mothership has an AC and a damage threshold, allowing it to be attacked with the normal rules for attacking objects. Ranged attacks and spells are viable options that allow the PCs to keep their distance. The PCs can also choose to board the mothership and attack it in melee. Any PC on the mothership when it is destroyed is subject to an effect, but each PC may first take a reaction. The effect does not call for a saving throw, attack roll, or ability check. The full (spoilery) quote from the adventure is as follows (Stardock Under Siege, p. 34):
Anyone on the nautiloid when it is destroyed may take 1 reaction before they are killed.
This reaction is presumably granted at the end of the round when the mothership is destroyed, after damage has been reported from all tables. Since the adventure does not list specific valid reactions, I assume that only the standard reactions are available. Are there AL-legal features or magic items that allow movement, teleportation, or appropriate defenses as a reaction with a relevant trigger?
Bonus points for solutions that work for a variety of PCs in Tiers 1-3, the tier range for the Epic. The party also needs to damage the mothership, so "just keep Readying movement" won't work, unless the party as a whole can still deal enough damage.