Stealth is fun.
Shadowdancer may be one of the most popular Prestige Classes in 3.5e, and that is solely due to the Hide in Plain Sight feat. Many players enjoy the thought of sneaking invisibly to the enemy and rolling insane backstab/sneak attack damage.
Unfortunately, stealth in D&D is not always that fun.
Now, the backstab part is awesome, and that's why most stealth players enjoy it. The problem is that the D&D mechanics as they are played out in most campaigns do not make much of stealth beyond a canned skill challenge. By looking at some good stealth games for the computer, such as Dishonored or Assassin's Creed, we can take some tips and add them to our campaigns.
Objectives
This is the biggest change that a DM has to foster in his campaign. As mentioned before, the objective of stealth is almost always just to get in some extra sneak attack damage. Stealth gets boring when, in the end, it's only about combat. There is nothing wrong with sneak attacks, of course. Some of the most memorable moments in my campaigns have been sneak attacks (double crit + 4x backstab damage FTW?), but stealth needs variety.
The purpose of stealth is to remain undetected. Let stealth be a tool for defeating encounters. If the players successfully sneak around an entire group of hobgoblins, give them full XP as if they had beaten the fight. And don't just stop there. If you want great stealth encounters, turn it into a real challenge like Dishonored does. Make enemies move around somewhat unpredictably. Have your players use distractions, or find opportunities to pick off the enemy one at a time. Give them bonus XP or a better reputation for being able to complete encounters without bloodshed, similar to Dishonored. Also like Dishonored, make a few combat encounters really dangerous if you rush right into them, and be sure to make that fairly clear through in-game information.
Environment
The world is bigger than a grid. Description helps. Open up the terrain for movement, like Assassin's Creed. Let them sneak past the royal guard by balancing across the rafters of the great hall or by sneaking over the rooftops to bypass the thugs waiting for them in the street. Think in 3D even though the grid is 2D.
Light is a huge factor for stealth in a lot of games, such as Amnesia: The Dark Descent. It ought to be very important in D&D as well, what with all the torches, lanterns, and magical lights often found in its environments. Have players make strategic use of light. One campaign, my players doused a torch while the guard was on the other side of the building so that when he came back, he couldn't see them sneaking inside. Unfortunately, the sudden lack of light alarmed him, which leads to another point:
The Chase Sequence
The way you describe the ninja character as cycling through backstab -> run -> hide -> backstab definitely confirms this as a bad pattern of stealth. One of the biggest flaws of the first Assassin's Creed game was how you could stab someone, run like heck, hide on a bench right around the corner, then go back and stab someone else. Rinse. Repeat. Worst of all, until they introduced notoriety in later games, it seemed like everyone forgot what you did.
Dishonored is a much better example of how to do detection and chase effectively. On the very first detection, the enemy is immediately alert and aware of the fact that you do not belong here. Hostility begins right away, and the chase is brutal. In a chase, NPCs do not let you get away unless you do something really daring. In the TV Show Burn Notice, the main character remarks during a narrative in a chase sequence that the only way to escape a chase is to do something that the people chasing you won't do -- like jumping off a roof.
And even if you get away, the NPCs should not just "forget" about you. They should be on high alert until you die or they are convinced that you have been driven off. Enemies on high alert for a stealth PC should not be easy to catch off-guard. In addition, they should not be splitting up alone if they are even reasonably intelligent.
Have NPCs adopt tactics like the PCs tend to act when encountering stealthy foes.
All Alone
"But I'm the only stealth character on the team!"
This is roughly the ninja player's position, I take it. I've been there. Fortunately, you don't have to be reliant on stab-and-run to be useful. A number of the former tips are intended for stealth-based encounters, but here's what a stealth PC has gotta do to have fun with stealth while your allies are kickin' down doors in the name of Tempus:
1: Wait for the encounter to get started. Be out of sight on the periphery.
2: Sneak up to a squishy target.
3: Stab.
4: ???
5: Profit.
An ultra-stealthy character is ideal for taking out priority targets. Then, using other skills, such as acrobatic-type skills, make a daring escape. Not just running away by pure movement points, but dodging between pillars, leaping onto ledges, or tumbling past enemies to rejoin your allies.
Stealth should get you into the fray. Speed and tricks should get you out.
First, this adds variety to your actions as a stealthy character.
Second, it should be hard to lose detection when enemies are tracking your movements so closely.
Beyond combat, a stealthy character can still be a great asset. Perhaps you can open a gate while the party is fighting. Maybe you can sneak into a camp and rescue a prisoner while the party is attacking from the opposite side. Generally, you should avoid going too lone wolf unless your party wants you to do so, because that's dangerous and slows down the game for others. Performing a stealth mission while the party fights a battle has been the best possible scenario in campaigns I have played. It keeps everyone busy, provides a distraction, and lets your group benefit from stealth simultaneously.
TL;DR version: Stealth should be more than dice rolls. It needs to interact with the environment and the intelligence of the NPCs involved. It should be rewarding, fast-paced, and require cleverness more than just sneakiness. When done right, it should give the party big advantages as a whole.
It’s quite common.
Banning high-end (and low-end) material is a very common practice. It’s massively more effective and sensible than, say, banning books X, Y, and Z when your goal is to have a certain power level; it gets right to the heart of the issue you’re looking at.
In my experience, however, it’s better to just ban Tier-1 characters. A single level of cleric, while very good, does not make someone a Tier-1 character, but it does enable a lot of other options (Travel Devotion, various Divine Feat options, paying feat taxes efficiently, etc.). Single-level, or few-level, dips in archivist, artificer, druid, or wizard are less frequently desirable, but I can think of arguments for each.
By the same token, it’s pretty common to want players to avoid Tier-5 characters, but sometimes judiciously using a Tier-5 class is appropriate – a couple levels of paladin for Divine Grace, a level of monk for the feats, whatever.
So yes, tell the person playing the cleric that the class is too powerful for the game you’re DMing, and maybe you’ll allow minimal use of it. Tell the player who thinks monk is a good idea that it’s not, and that you need characters to have more power than monk offers in order to be able to make your life easier. A level, to get a punch of relevant feats – fine, if you must. But only if you’re grafting that onto something that could really use it, and be competent.
And it does sound kind of like some of your players are in a place where even allowing minimal usage may cause problems, just because they do seem liable to try to weasel their way into getting more out of you. At least the first time, it may be best to just say “no,” though again I do recommend in general to allow judicious, minimal use of classes outside of the desired tier-band, whatever it is.
Because you are absolutely right – DMing for split-tier parties is extremely difficult and frustrating. In fact, avoiding that situation is exactly the stated purpose of the tier system. See JaronK’s tier list for classes, in the intro spoiler:
Thus, this system is created for the following purposes:
- To help DMs judge what should be allowed and what shouldn't in their games. It may sound cheesy when the Fighter player wants to be a Half Minotaur Water Orc, but if the rest of his party is Druid, Cloistered Cleric, Archivist, and Artificer, then maybe you should allow that to balance things out. However, if the player is asking to be allowed to be a Venerable White Dragonspawn Dragonwrought Kobold Sorcerer and the rest of the party is a Monk, a Fighter, and a Rogue, maybe you shouldn't let that fly.
(emphasis mine)
The reason anyone cares about tiers at all is to attempt to recognize and address that situation. You are intended to look at the tiers, pick a certain tier or tier-band, and use that as a guide to keeping all PCs on roughly equal footing so that DMing becomes more manageable. So yes, this is “OK,” at least insofar as common wisdom is concerned – it’s actually the whole idea!
- By the way, if your players are looking for acceptable alternatives to favorite classes, this answer may be a helpful jumping-off point.
Best Answer
Any of the classes can work well together.
Classes in D&D 5e aren't all that black and white. A Fighter with a Criminal background, for example, can participate just fine along with a rogue - in fact, that's the general setup for Fafhrd and the Grey Mouser, one of the best known fantasy duos ever.
Fretting about class niche over "what the people actually want to play" is misguided, and it's only tangentially related to the problem and its solution. The real trick is in two parts.
The players should work together to have a shared interest. Regardless of class and crunch, if one player wants to be a socialite in the King's court and the other wants to be a dungeon slashing killer, that's going to be hard to accommodate. But it's not about the classes per se. A "cleric" and a "rogue" can tweak domains and backgrounds and skill choices to align well on anything from "we are holy inquisitors" to "we are underworld figures." You need to worry more about one wanting a religious aspect to the game and the other not. Make them work that out, it's not your job as DM. Of course if your campaign is going to have certain elements you should tell them... "This will be a scholarly campaign about tracking down forbidden books, like that Johnny Depp movie!" will signal to them that a pair of illiterate woodsmen will not be a good choice.
You the DM then need to adapt the campaign in play to accommodate whatever they picked. If it's a cleric and a thief, then they're not going to have as much raw kill in their backpacks as a barbarian and a wizard. Just as there are many solo adventures designed for a rogue or a cleric or a monk, you tune your game to fit whatever their overlap of interests is. Heck, they can be the same class for all you should care. If they really, really need something they can't provide (spellcasting, healing, a bodyguard) well that's where hirelings come in. This is basic encounter scaling and planning, like you'd do for any real party with its strengths and weaknesses.
In the end, every combination is going to play differently and have some pros and cons. So go do it! Go discover this through play. There's really no choices that will "break the game", so meta theory land is the wrong place to be addressing this. Play the game. Have them pick two and see how it goes. If someone dies, then decide if that combo wasn't working for you and roll up something else. There is no wrong answer.