This can be done weekly or biweekly, at predetermined random time within the week (or 2 week) that is annouced one round ahead somewhere.

Defender: one of the legions with the current top level base(if there are less than 5 of that level, then the top 2 levels of base) and its allies. If a defense was successful, the next defense is done by one of the ally who meets the condition(of top level base), if the defense failed, then the top-damaging legion in the base war that meets the base level requirement is the next defender
Attacker: all ships in the galaxy other than the defender

Rules:
All ship that attacked the base at least once during the event will be put into a list. For any defender player that choose to particpate, all ships they see on the BT are ships from this list only, rank range limit is removed.

Repair nanos have a cd of 2 min for attackers.(no limit for defender, and shield restore is free to use to all)

For this event only, when a base ability is activated, the number of players counted toward the ability also include all players in the battle pact.

About race change of defender side only, one of 2 plans:
1. during this event, 2nd and 3rd race change are free, 4th and onward are 80% off. (1st is normal price) A racial change artifact will grand 2 additonal free race changes. All free race change are canceled at the end of the event.
2. during this event, race change is free, but cannot use any racial/class ability during this period and any bonus provided by the race/class does not work outside of PvP battles. if a free change is used, and the race/class is reverted back to orginal (before the war) when the event ends. There is no cd for the first race change, a 1 hour cd after the 2nd change, 1 hour 30 min after 3rd and so on. Thou you may use paid race change at any time w/o affecting the cd.
In addition, any action performed during the event(regardless of which of the 2 plan) will not count toward race specific achievements (use NI, claim daily etc)

There will be a 5 min prep period before the war during which time the above two rules (inclusion for base ability and race change) are in effect so the defending legion can buff up.

Attackers cannot use halc trap or calming amp, ones already used will be disengaged upon firing a shot at the base, and once a shot is fired, they cannot be used again for the duration of the event.

The disable action limit of an attacker will be set to 1 if it is 0 whenever he fires a shot at the base or any defending player.

Optional: during this event, base hull and shield is incresased
Optional: during this event, base ability point regeneration timer is reduced (somewhere between 1 hour and 10 min perhaps)