Balanced Units - A minimal balance mod for units

and the vortex deals +60% melee damage

The enemy will position themselves in such a way that attacking multiple units becomes disadvantageous/impossible. I would rate it as +40%, or maybe +50% damage at most.

Are there any dissenters left?

I don't know. Applying invisibility also means automatically losing one turn. I think three turns was a good balance. Assassins just need to be made stronger. For example, remove the penalty to ranged attacks. Or give them armor-piercing, like archers, for close-range attacks.

An alternative is 75% chance to hit + agility; it's a matter of personal preference. 75% was used in RTA and TE, while 100% was used in WGE. Let's share our opinions.

100% chance to hit without agility. But you could give them counterattack, which would allow them to maneuver fearlessly in any way that is most advantageous, while still preserving the original concept of a "glass cannon" for this tier of TE.