How "balanced" or broken is this homebrew item?

[martinaj]

My party is going to find the first piece of a homebrew artifact this Sunday, and I've just about figured out what it does (besides being a macguffin), but I'm still tuning its mechanics.

Background in spoiler to avoid wall of text:

It's essentially a universe egg (it contains the genesis of a new universe, and could be used to bring a new one into being and functionally destroy the existing one if all of its pieces are brought together). It was formerly a major part of Kasatha mythology and inspired the first Solarian, but that information, in fact it's very existence, was lost in the Gap. They called it the Cosmic Principle, and each piece (still haven't decided how many their are) is essentially an uber-battery, bringing the power of the cosmos to amplify whatever it's plugged into, with multiple pieces being able to influence the cycles of entropy and genesis if they're re-united. I'm thinking I'm going to tie its shattering to a ritual that was used to move Golarian and strengthen Rovagug's eroding prison, so the Cult of the Devourer will get involved before too long (I'm going with the Rovagug = The Devourer in my game), and if the game goes on long enough the party will be able to use it to rediscover Golarian and destroy Rovagug. I was thinking of making the Starstone the final piece, and the fact that it was "missing" when the rest of the thing was used to strengthen the prison is the reason it didn't have the kick to create a permanent solution. Still working out what all the other stuff will do.

So I'm still working out what exactly it will do as more pieces of it are brought together, but I've at least got the mechanics figured out for what the one piece will do, but I wanted to double check here to see if I was introducing that would be truly game-breaking into my campaign.

Basically, it's a modular artifact that any character can "plug in" to one of their major class features to give it a boost, but with a cost, and it's generally a difficult-to-control double-edged sword. Here's what I've got for the classes that comprise my party. Any ideas on effects for the remaining three classes would be swell.

Solarian:

When used as a weapon crystal (can also be plugged into solar armor), it accelerates their attunement, allowing them to become fully attuned after only 2 rounds. However, a zenith revelation of their choice (so no choice till level 17) ALWAYS activates as soon as they hit full attunement, and on the following round they immediately attune to the other solar mode, with the process continuing to repeat itself. Each time a zenith revelation activates, they must make a DC 18 Fortitude save or become fatigued. If they're already fatigued, they become exhausted. If already exhausted, they pass out for 1 minute and the process ends. The thing WANTS to be used once plugged in, and removing it manually requires a DC 18 will save)

Mystic:

This one didn't give me as much to tie to without coming up with something specific for every connection, and nuh uh. So instead it changes and amplifies their spells. They can spend 1 resolve point and channel a spell into the shard as a full action. This requires intense focus and causes the Mystic to become staggered until the end of their next turn. Doing so summons 2 aeons of a level appropriate to the spell level they used, lasting for 1/round level. These aeons, however, are not under their control. One of them also can cast Mystic Cure (of a level of the spell used to summon it) once per round, and every round, it will attempt to heal whichever creature is missing the most hp within 30 feet (except the other aeon). The other has an extra +2 to its damage per level of the spell used to summon it, and will always attack to the best of its ability whichever creature within 30 feet (except the other aeon) has the highest current hit point total.

Mechanic:

This thing affects the mechanic's AIs, boosting its performance by helping him link it more directly with his own mind. The extra information their brain processes, though, can be difficult to manage. They functionally gain a latent mental disease, and it gets worse whenever they take advantage of the shard's abilities. When they fail a save, they will move one step down the track, but move up one step with a full night's rest. Obviously, this affects the drone and the exocortex differently.
For a drone, the mechanic can, as a free action, boost his action efficiency. For the next 2 rounds, requiring only a swift action for the drone to act normally, and requiring the sacrifice of only a move action to grant the drone a full action for the round. Any time he activates this ability, he must make a DC 18 will save or move one step down the mental disease track.
For an exocortex, the shard allows the mechanic to lock onto one additional enemy. Furthermore, when they full attack, the mechanic reduces the penalties by -2, so long as he targets two separate targets of his exocortex. Whenever they make such an action, they must make a DC 18 Will save or move one step down the mental disease track.

Technomancer:

The shard can function as a spell cache, modifying the way the ability works. The technomancer can spend 1 resolve point as a full action to draw upon the power of the the shard to power their spell, but tapping its power so directly exposes their body to cosmic energies. They can cast any spell they know, increasing their caster level by 1 and raising the DC by +1, and this spell does not use up a spell slot. The technomancer takes 3 points of damage per level of the spell cast, and this damage is dealt directly to their hit points, even if they have stamina left.

[Tacticslion]

Sounds like a cool concept, though I'm leery on the specific executions. Not bad, exactly, but they feel a bit thematically out of synch with each other - like they should belong to different shards. Beyond that, though, this is a dot for now - more thoughts later! And really cool idea!

[Space McMan]

I'm most familiar with the solarian class, so I'll speak to that one at least.

It's absolutely not worth the cost. The save DCs are very high. A solarian who hasn't taken improved fortitude and iron will won't be hitting a 50% chance to make them until around level 10. So the player must assume they're going to fail those saves more often than not until high levels.

In exchange for being exhausted and unequippable, the solarian MUST use their revelation every other round. They do get a choice by level 9, since they get two revelations at 1st level, and two more at level 9. Until level 9 is reached, that's already unappealing. Black Hole is straight up terrible, and while supernova is better, it hits allies and is less valuable against opponents with good reflex saves or fire resist. There's no chance I as a solarian would ever exchange progressing exhaustion for cycling supernova and black hole every other round.

But by far the worst property is the fact that the artifact FORCES the player to switch attunement every other round. A melee solarian never wants to be out of photon mode, and a ranged solarian never wants to be out of graviton mode. If this part didn't exist I doubt a solarian would ever use the item anyway, but with its inclusion it becomes a serious detriment to be avoided at all costs.

You need to back waaaay of on forcing classes to use their mechanics in certain ways. Solarians don't want to switch modes in combat every other round, and they don't want to use their revelations every other round either. If you keep the high DCs on the items bad effects, you need to give it strong bonuses players can use as they choose, not as you dictate.

[martinaj]

Well, that's why I made it an artifact, and it's value calculation isn't included in my party wealth calculation. Artifacts are supposed to be dangerous and come with a "curse" of some sort, but they aren't forced to use them.

If they hang onto them, they're going to be fairly modular, giving the party to either combine several pieces for heightened effects and easier control, or spread out smaller chunks so everyone can use them at once. But yeah, I guess when you put it that way the Solarian effect seems pretty harsh. That was the first one I put together, so maybe it needs to be tweaked a bit.

What if I just took off the forced attunement swapping and forced activation? Then it becomes "you can quickly spam one of your zeniths, but if you aren't confident in your saves you can only do it for a few rounds"

[Space McMan]

Yes, if make it so the artifact allows the solarian to use their revelation every two turns, but they don't have to and don't make a save unless they do, that would be a lot more reasonable. It's still not a very strong effect but it's at least a net positive effect.