Unlocks at 4 stars
Event requires you to complete 4 tiers with 4, 5, 6, 7 star ships. Once you complete the 4 tiers you unlock the Executor at 4 stars. This also unlocks a bonus tier that rewards 10 ship blueprints that is replayable every time the event returns. The bonus event can be refreshed 19 times for 999 crystals each time. Packs will be available after meeting the character requirements at 1250 crystals for 10 blueprints (with no limit on purchases).
The event is expected to run 1 time per month but may change its frequency in the future
Below is the cost to star Executor during one event. If you are grinding Executor over several events then this won't be relevant. This assumes you will refresh the event as many times as needed before buying packs.
4 star - 0 crystals
5 star - 5,994 crystals
6 star - 13,986 crystals
7 star - 25,231 crystals
These requirements are necessary before you can even attempt to do the event.
Playable for free once per event. Replayable 19 times at 999 crystals each.