As you can see, stealth can easily reduce the skill level of classes and reduce meaningful skilled choices players can make to adapt to it. Especially in Guild Wars 2, stealth can make it so you win fights by mechanics, not by skill. So how do you balance stealth in a game with all these massive advantages it gives? It’s very logical and quite simple. I’m going to refer to three examples I feel are extremely well balanced stealth mechanics in PVP games: The Mesmer, EVE online, and Smite:
• Remove stealth or do not include stealth
• Remove the ability to do anything useful after stealth
• Design your game with rock, paper, scissors balance
• Keep stealths short in duration
• Increase the number of untargeted spells
The first is the most obvious. Just don’t have stealth in your game. Stealth is such a powerful mechanic and designers really need to see the role very clearly for stealth before including it. Don’t just include stealth because it’s the hip thing to do. Including stealth in a game is by no means going to increase the reception of it. Quite the opposite is true if it unbalances the game in some way. Also, make sure if you do decide to include stealth make sure your engine can handle it properly and it’s not buggy. There’s a lot of complex things code wise that stealth needs to do in a game. If your game simply cannot handle stealth from a base perspective, think of another way to fill the niche your game needs. This is rather impractical in Guild wars 2 as the design team has already committed to using stealth. However, they could make stealth simply turn the Thief shadowy and make him untargetable but still visible. This would make them still susceptible to AOEs but still give them the ability to mitigate most kill strike burst damage. This could make for a very interesting and balanced alternative in my mind, but still shouldn’t have more than a 5s duration on non-elite skills.
Removing the ability to do anything useful after stealth means quite simply you only want it to be used for scouting purposes. Trying to make a high damage low survivability class stealth is completely impractical. Make it so they can burst a target quickly and it becomes a one sided fight of “can the stealth character choose their targets properly.” Make the stealth class do too little damage and the enemy simply turns around after being engaged and guts them like a fish. The balance line is so razor thin it’s best to avoid it altogether. Having stealth characters do no damage isn’t practical for a lot of games but games with big open worlds, sandbox games, and other creative uses can often make use of a pure scouting or support role. It could be tweaked to make sure the class that can stealth can only use support functions like CC or buffing friendly players. This has the added benefit of increasing communication and team play as the stealth class generally cannot solo kill anything but can be a force multiplier for their team. If you want a great example of well balanced stealth support and scouting, EVE online does is splendidly with 3 different classes of stealth craft. One class can only really scout enemy systems, the other can do fairly decent CC but very low damage, and the third is only good for fleet logistical purposes. This is impractical for Guild Wars 2.
Another from the design perspective, balance your game in a rock, paper, scissors fashion. Make it so stealth characters counter something, but something hard counters stealth characters. You see this in MOBAs frequently and some RPGs. I think it’s good balance as it emphasizes team composition, positioning, and sticking together much more but other players dislike it. It promotes strategy at the cost of reactionary tactics. What you’ll often see is warrior characters having decent CC and physical mitigation, but low maneuverability and mage characters doing high armor ignoring damage but with low escape and survivability. What ends up happening is if a rogue engages a warrior the warrior brushes off most of the rogue’s damage and caves his skull in with CC and damage. If the rogue stealths up to a mage he can gut the mage in a matter of seconds leaving the mage with little defense. Mages by contrast do heavy damage to the warrior as most of their damage is unmitigated. You can throw in other things like support characters and objectives to make sure the team is focused on supporting each other instead of running around mindlessly TDMing each other. This has the added factor of increasing balance. If the rogue gets a huge buff for some reason teams need only to increase the number of warriors to compensate which then makes mages more viable etc.