I believe that the Advent Rebel's "Wail of the Sacrificed" tec was just used. That planet's broadcast center just used it, thus the animation. This ability, once researched, can be used at any temple of communication, but it is wise to only use it on worlds that border a gravity well that belongs to an enemy or has an opposing player's fleet. Say that I have a planet with 100 population. If I use Wail of the Scarified, each population does 20 damage to all enemy structures and ships, and in this case it does 2000 damage. You will also lose your planet.

I advise you to build a starbase on your planet and put Induced Reverence on it. When you do, you can use Wail of the Sacrificed without having to recolonize your world.

That's genocide space fist.

Is there any way that that can be countered short of not having ships near Advent rebel planets?  That sounds severely overpowered--it's like a traveling missile barrage that occupies many gravity wells.  I wasn't real familiar with the ability until I lost about 600 supply points of worth of fleet to it today.

It's so situnational that it can be justified to be so stupidly powerful. Unless you actually score a desert or terran planet that connects to at multiple enemy worlds or strongpoints it is just a mediocre support ability. It it pretty much one-time use and can be stopped (as others have mentioned) by reducing population on the enemy planet.

From an Asteroid it does 20x20 damage max, that's 400 damage.

From a Moon it's 20x30, 600 damage (--> this is where your lighter frigates start dying if you didn't research shields and HP)

From a Volcanic planet 20x70, 1400 damage (--> this is where lighter frigates and some cruisers die)

From an Ice planet 20x160, 3200 damage (--> if your enemy has a massive frigate fleet try this for instakill)

From a Desert planet 20x247, 4940 damage (--> this is where it gets dangerous for your structures and capships)

From a Terran planet 20x322, 6440 damage (--> run, Titan, RUN)

The damage seems to ignore armor multiplyers and instantly kill constructors starting with volcanic worlds, but as I said, actually getting a planet close to your enemy, getting the population up to the highest level and attacking them with it requires some serious effort and some luck on your side. I consider it more of a "break free" ability than an actual superweapon replacement. Not to mention you wont be using it twice if it fails.

As far as I know it isn't affected by armor, though (unless that changed in the recent patches).

By itself it doesn't worry caps or titans, but your regular cap or titan has its shields removed or severly reduced. Remember the ability is usually used in conjunction with an enemy attack and may turn a superior fleet into an inferior one.

I thought level 2 on red button only increases range, not firepower...