I'm thinking how scorpion can be reworked to be interesting, and very different from ulti and dante.
The cloak is nice, but it shouldn't be like ulti: big damage burst from nowhere, and huge single target DPS that melts heavies, but is very weak to anything that it cannot hit fast enough.
I think it can be differentiated from ulti by focusing it more on the stunning role: buff stun time of multistunner a bit, give the lightning more AoE to make it stun groups and heavies a bit more reliable. (although it should not be super effective vs heavies, this is the ulti's role)
Giving it more DPS would make the opponent's reaction window too small, it would be nice if the appearance of a scorpion poses some interesting counterplay: if you can send in more units to attack the scorpion from a different angle (which it kinda does already, which is interesting), you might be able to decrease the scorpion effectiveness. The scorpion would then benefit from allied units that support.
Now come the stranger ideas:
What if the scorpion would in some way become stronger over time after uncloaking? One way would be a weapon that has to warm up after cloaking (gatling gun?), it could get increasing dps as long as the scorpion is firing and stationary.
Or a mechanic that makes it stronger vs lighter units (to prevent overlap with ulti):
Give scorpion the power to munch up units/reclaim their wrecks and turning them into ... fleas/spidery drones/ that assist in dealing damage against stunned units. After an engagement these units could crawl back into the belly of the mother spider (uhm, scorpion)/ sit on top of it. (2many drone units)
vs heavies it would not get this dps increase and would have to rely on assistance or earlier kills.
This would also provide an possibility for reactive counterplay: reinforcements can decrease scorpion dps by killing the drones.