It was more of an issue early on in the war, but a Spooka’s more cutesy appearance and smaller size are pretty deceiving. Children who didn’t know any better about fusion monsters would approach them unwittingly. Even in the present, soldiers that aren’t used to facing this type of fusion monster can let their guards down around them to their own peril. Watch your back, because these guys will go from just a little spooky to downright sinister in an instant.
As mentioned when discussing the Soulos, it was revealed in concept art that Spookas can have little ghosts hovering around them. I’d like to think of these ghosts as pre-formed Spookas, transitioning from the typical fusion spawn to a more humanoid form based on the spirits that lurk in graveyards. However, they’re so weak in this state that they are hardly ever seen in combat. It’s also a very rare case of fusion monsters showing a protectiveness over some type of--and I use the term loosely--“offspring.”
While this can be due to, in part, their pack behaviors, it also likely has something to do with the nature of the Spookas in-particular. Their description mentions that “the heart of this ghost beats for the long-lost love he's still searching for.” Since they are still incredibly aggressive against other lifeforms, this seems to be a trait they just happened to mimic from the lost souls they’re based on; beings that have lingering attachments/desires in the mortal world. They may attack people like any other fusion monster, but they are fiercely defensive of each other or anything they view as theirs’.
Because of this, a simple way to maneuver around the Spookas is to disguise yourself as one. Though they have been used for recon jobs by Fuse such as in the mission “Spooky Spies,” they’re not too bright overall, so a well-made mask can easily trick them. The main downside to this is that it can work too well at times, risking the chance of the Spookas following you around until the jig is up.
Their main weak spot is the large “heart” that can sometimes be seen beating out of their chests. Stronger Spookas are pretty good at containing it, but when they are weakened in-battle or experience bursts of intense emotion/stress, that heart is more likely to show. It’s very cartoonish, but does have the practical purpose of pumping fusion matter throughout their bodies just as the human heart beats heavier to increase cardiac output. Still, since it is such as exposed weakness, it’s possible that they developed this by mimicking ghosts similar to the Bleeding Heart Bride from the Haunted Mansion, intending to hide themselves with the dead or Underworlders.
Again, a fusion fighter shouldn’t be tricked by their appearance or behaviors. The Spookas are just copying what they’ve seen mostly human spirits do: They won’t hesitate to attack actual human beings. Furthermore, while Spookas copy the behavior of ghosts attached to the mortal world through some kind of longing, their cousins, the Spinetinglers, copy ghosts attached to the mortal world through malice. They’re stronger and exhibit even more aggressive behavior than the Spookas do.
Doodled a little Spookas/Duma Faithful Lukas for @redmessenger because their AU hurts my soul. I swear this is not the context in which I'd intended to draw freckly Lukas.