CONDITIONAL SKILLS CONCEPT

Only way to know is try *shrugs*. The ones with negative outcomes the players probably not going to want to use unless the initial attack is so good its worth the tradeoff. Also how informed of the player is of the outcome? What is the reason for choosing one state over another. I would even go further what if certain enemies do state changes based on a state that were given. (Get hit by lighting while on fire, turn into some weird unstable nuclear state or something wild). Maybe there's a skill that transfers a state from one enemy to the rest etc.

But same as every battle system with possibility permutations: it takes a lot of experimentation and trying out stuff.

This is a really cool idea. Reminds me of Divinity: Original Sin (1&2). It's what I would want to do if I had the means. I don't know of many games other than the aforementioned that does this (or do it well).

Take people's advice with a grain of salt when it comes to things like making battles more challenging or longer. I've been noticing a trend of forgetting about battle's entirely or making them quickly skippable so go with your gut. To me this sounds like an amazing idea, but I've always been more interested in great battles than other things.

author=AlphaMad
Greetings,
I had an idea for a battle system and wanted to see if you think it would be fun or annoying. I'm not worried about the feasibility yet.
I want attacks to change depending on certain conditions, specifically status effects. For example, if an enemy is on fire (status effects) and is hit with a concussive attack, the fire damage would spread to nearby enemies. Another example would be if an enemy is in a shock state (electric status effect), then close range attacks like punches and swords would result in shock damage on the player. A third example could be if an enemy is frozen, laser attacks refract and hit nearby enemies.

I guess what I'm asking is would this make battle exciting and fun to experiment with or obnoxious and cumbersome. My game is in a near future/sci fi type setting. Battles will be far less than typical RPGs but longer and more intense.
Also, do you have any examples of combinations that I could add to my list? Appreciate your help.

Hmm...
Maybe with the fire one, it could be:

Switch Automatic "Fire Spread"
IF EnemyA is able to act
IF EnemyA "Aflame"
Add Condition "Aflame" Enemy B
Add Condition "Aflame" Enemy C
Add Condition "Aflame" Enemy D
Display Message "The flames are spreading to the other enemies!"
Turn Switch "Fire Spread" OFF

That one might use a common event to make it work correctly, and I for see it using Battle Events that you would have to make a separate Battle Event that can be copied many times.

Maybe for the freeze one could use no movement in a status with reflect on them??

The shock one seems harder to do

I would advice trying to look at whatever you want to implement from the eyes of the player. How will the player use/abuse the feature you planned? Let's take the laser and ice as an example. I will assume that only the second target takes damage, otherwise the strategy will be very obvious, milk the refracting for all it's worth to double laser damage. With only the second target taking damage, the refraction will not be that useful for the player when it comes to single target laser attacks. Chance is the player will just target whatever enemy they want to injure rather than targeting the enemy that's frozen and then see who the attack refracts to. On the other hand, it will be annoying when the enemies uses that feature as it ensures they will focus their damage on a non disabled character instead of the one that has been disabled. Typically, if you have a disabled character and one that's not, it's better if enemies KO the disabled character.

With multi-target laser attack, it gets interesting, especially with multi-target freeze as well. You can freeze enemies and then cast the multi-target laser. By doing so, the damage gets concentrated to the enemies that aren't frozen, which are the enemies that you want to kill first.

By seeing things from the players perspective you can easier decide how exactly the rules of the conditional skills should work. Assume there is a boss that has 4 minions. Do you want the players to freeze all minions and then throw multi-target laser attacks so the boss takes 5X damage? Is this sort of strategy expected, optional or maybe it just doesn't work that way. Design the rules so it encourages the most fun interaction.