These use a very interesting Default attack which is different to others.
They attack twice with a normal hit, and then do a 3 hit combo attack.
Base damage is very good.
The Default attack has 75% of physical damage converted to lightning damage and a scaling more damage multiplier which goes up to 200% at level 84 spectres.
It also has 25% less attack damage.
They also have a Flicker strike on a 3 seconds cooldown that has 50% of physical damage converted to lightning and 30% less damage.
They also use an enrage ability which has an uptime of 6 seconds and is on a 12 seconds cooldown.
They use this ability as long as they are not on full health.
It is hard to figure out what this enrage ability does exactly, but enrage mechanics on monsters are usually around a 20% increase to attack speed,size and movement speed.
These have 75% lightning resistance and 0 of the others.
They have about 45% the life of a Primal Crushclaw.
Overall,
This should be a very good spectre.
With multistrike they flicker 3 times, if then combined with melee splash their clear should be phenomenal.
Their Default attack is a bit better than it looks on paper, it lists a slow attack time of 1.7 seconds but because of the combo attack it seems to be quite a bit faster.
Seeing as they have a combo attack however, multistrike can also be a downside as they stay locked in place for quite a while, you would probably want to swap multistrike out for something else on faster bosses.
These use a monster version of Flicker Strike, meaning it's cooldown cannot be expended by using frenzy charges, I illustrate this at the end of the video.
You would not want them to use too much Flicker Strike anyway, as their default attack is far stronger.
These can be obtained from Verisium Ore nodes in the 3.25 league mechanic.
This video was recorded in patch 3.25.