Homebrew special ability for invincibility

Question

Concept

(spoilers in first and third links)

I'm interested in creating something along the lines of the Dahaka from the Prince of Persia: Warrior Within game. In summary, it's invincible throughout the first major section of the game and every time it comes up the main character's only option is to run. Eventually it can be challenged to a fight -- made only all the more satisfying because of it's former invulnerability, in my opinion.

I want to pull this off via a teleport trick. Think this question only with a "yes" answer instead. In this way, the creature would be impossible to hit without some sort of forbiddance, dimensional anchor or other effect, and it's demise ideally wouldn't occur until that segment of plot when the party/character has found an item able to kill it (magical forbidding weapon, artifact, etc.)

Question

If the creature can use a short-range (30' or so) teleportation as an immediate action, how can I keep the party from turning to face it before they find a plot-item keyed to its weakness? Already I'm figuring on keeping the two aforementioned spells away from them. How else do I need to prepare in order to pull this off?

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As Brian Ballsun-Stanton noted in his comment, this is a puzzle monster. In tweaking the rule, my aim is to keep its weakness consistent. Thus, if teleportation is how it works, then it won't work in the area of forbiddance/etc. It's not my goal to chase the PCs all over the campaign world: short chase scenes for plot's sake with an end either within or just out of sight (like an area with innate forbiddance effect if teleportation is used). The Dahaka was loath to enter water so all the Prince needed to do was find and cross a body of water (almost everywhere in that setting, as it was how the Prince replenished health).

My goal with this question is to find how to rework the invulnerability to compensate for loopholes (effects dispelling it, etc.), but also to support this ability with rules. Too much more fiat will make it difficult to keep the ability working in a predictable fashion -- very important to this creature's purpose/setup. Encouraging the party to flee is covered over here.

Answer 1

To create the effect of the Dahaka in your plot, there are two basic elements you need: the creature must be unstoppable (but escapable) until X happens, and then defeatable with X.

And for this to work, the most crucial point is that the party must know that. Knowing they can't win, they'll run and look for a way to win. If they believe they might win, they'll try... and feel railroaded when they can't. Clear signals will be very important.

Being Unstoppable

There are a few obvious, and some subtler, ways to accomplish an unstoppable monster. I won't give an exhaustive list, but a few possible choices are:

• Immediate Action Teleport, as you suggest.

  This is a flavourful choice, but it creates some problems as well. The party will try to retreat into small, underground areas to trap it, or use ranged multi-attacks (how many IA's were you planning to give it each round?) And if it can teleport that quickly, it can pursue them anywhere... which is a serious downside. You need the party to be able to run away from it.

• Damage Reduction {lots}/{special}.

  A creature with DR 20/alchemical silver is pretty much invulnerable to a lower-level party that doesn't have it. If a little damage gets through from big attacks, that's OK - it reinforces that they can't do enough.

• Ethereal / intangible creatures have the same considerations as damage reduction, but with extra spell options to consider.

• Regeneration.

  Consider a golem with Regeneration 10 (that's not prevented by the usual counters). The party can put it down... but then they still have to run before it gets up.

Bear in mind that it's chasing them, so the party can probably get it into any environment of their choice. Have answers for what it does in any case.

Making them run

The key element of preparation isn't making sure they don't have spells that beat {method of invulnerability} - although obviously you need to check for that. It's making the party believe what you want them to believe. So now you need to scare the party into running.

Gauge your creature's attack damages very carefully - it needs enough damage to scare the party off, but not so much that it'll actually kill them if one or two try to battle it - which they probably will, either to win or to buy time for others to retreat.

• Have the {bad guy that unleashes the creature} boast of it's invulnerability.

• Make sure to describe hits carefully, so they understand that they're not really harming it.

• Include legends before they meet it of the unstoppable guardian.

• Have it break through a wall to get to them. Even if there was a way around... just have it keep coming.

• The movie classic: let a mentor NPC bravely sacrifice themselves while screaming "run".

The word you're looking for here is implacable.

Aiming for the turnaround

It's important to set positive expectations too. You want the party to flee not in "this is unbeatable" panic, but towards a goal - again, otherwise they'll feel railroaded. Give them solutions to point at.

• Before they meet it, give them legends that only {ancient hero} found a way to beat it.

  They can go research those tales for clues later.

• Let them improvise early solutions to buy time. Give them tempting pits to drop it in to, tunnels to collapse, bridges to cut - anything to let them feel victory. Let them get clear and gain a day.

  (Then it turns up two nights later at the inn where they stay...)

• Give them a clear goal early - let them figure out what penetrates DR, or the special item/ritual that prevents regeneration. Be prepared to say "yes" to clever substitutes.

Answer 2

Introduce the Opponent Early

You needn't adjust your game world to make this happen. Restricting teleportation countermeasures leads to a host of higher-level implications with which the campaign must struggle later. Thus, rather than potentially injuring your campaign's verisimilitude by limiting teleportation countermeasures at mid-levels when they become available, do this: Introduce the opponent early and make teleport countermeasures available normally.

According to the Dungeon Master's Guide 5% of encounters are very difficult (49), with ELs 5 or more higher than the PCs average levels. This means a creature capable of teleport ambushes can be encountered when the PCs are level 2. Yeah, 2. That encounter with a CR 7 foe will kill them if they fight. But that's okay! You want the PCs to have the encounter and run from it. Letting the players know their PCs are supposed to run--without just telling them--is the hard part.

PCs will want to fight that foe. That's what PCs do, after all. It's up to you as the DM to show the PCs they can't, and they must run or die.

That's definitionally railroading, so be prepared for grousing. You've created an encounter where victory equals cowardice... um, discretion..., and this will make the players uncomfortable. A sterling plot or epic triumph versus the foe later can make up for this, but don't expect the players to forget that time when you made them run away, and if you never get the opportunity to reveal that sterling plot or the players never get that epic triumph (e.g. the campaign collapses, other events cause a TPK) your credibility with that group may suffer.

Anyway, getting the PCs to flee means the creature must demonstrate his clear superiority over the PCs. Those demonstrations should involve death. I suggest introducing a slightly higher-level NPC whose purpose is to die at the creature's hands, the creature slaughtering a group of foes or allies whom the PCs encountered earlier, and, if those don't scare them off, the wholesale murder of animal companions. You need them to want to run, and, short of spells that render them frightened, most PCs just don't run.

Alternatively, the foe could just depart. He could be so contemptuous of the PCs that he just leaves. Mission accomplished, saving the PCs for later. It sounds like you want a chase scene, but I'm putting that out there because that's often more satisfying to the players than forcing their characters to flee.

The list of Dungeons and Dragons 3.5 creatures who can do what you want by level 7 is actually pretty long. I suggest a babau demon (MM 40) Wiz1 specializing in conjuration and possessing the immediate magic (abrupt jaunt) alternative class feature (PHB2 70). It can purchase a magical staff incorporating the spell fiendish quickening [trans] (BoVD 95) using 2 charges each for 720 gp per use (plus the flat 300 gp for the masterwork staff) to make his native teleportation even more dangerous. That, plus the nonelite array, his wizard spells, remaining gear, and hand-picked feats, should make him suitably formidiable.