I know of course that typed bonuses don't stack, but some ioun stones can grant multiple bonuses that work under the stacking rules, for example:

  • A cracked pale green prism grants either +1 competence to hit OR to saves. Is there a rule that stops one benefiting from two cracked pale green prisms (one to hit and one for saves)?
  • A standard dusty rose prism grants +1 insight to AC while a cracked one grants +1 competence to Initiative. Is there a rule that stops one benefiting from both a standard and a cracked one at the same time?

I'm most interested in Pathfinder rules here, but as a bonus...a DM of mine has a foggy recollection of that limit, so it'd be interesting to know if this limitation existed in previous versions of D&D as well.


4 Answers 4


This GM would rule that if two or more otherwise identical ioun stones grant bonuses on different rolls or to different values, a creature can gain the benefit of each otherwise identical ioun stone.

For example, this GM would have no difficulty ruling that a creature that sends spinning both an ioun stone (dusty rose prism) and an ioun stone (cracked dusty rose prism) then benefits from both the first stone's +1 insight bonus to AC and the second stone's +1 competence bonus on initiative checks.

Likewise, this GM would rule that the same creature can benefit both from an ioun stone (cracked pale green prism) that grants a +1 competence bonus on attack rolls and from an ioun stone (cracked pale green prism) that grants a +1 competence bonus on saving throws. Bonuses on or to different things that are from different sources generally stack, and in this case the sources are two different ioun stones, each having a different effect.

However, a stricter GM may want to apply the rules for Combining Magic Effects on Stacking Effects on Same Effect with Differing Results (noting, however, that such rules are usually applied in the context of spell effects) and declare the two identical ioun stones the same effect (for example, two ioun stones (cracked pale green prisms)) with differing results (for example, a bonus on attack rolls and a bonus on saving throws). Such a ruling would mean the creature benefits only from the last-sent-spinning otherwise identical ioun stone. This GM does not endorse such a ruling, but such a ruling wouldn't cause this player to abandon a campaign.

(Also, because the text on d20PFSRD is slightly incomplete, "For stones that have multiple possible effects…, the exact effect is determined by the item crafter when it is created and cannot be changed thereafter" (Seekers of Secrets 46). Thus, for example, it's not like a creature that finds an ioun stone (cracked pale green prism) and sends the stone spinning around its head itself picks the bonus; instead, the stone's creator picked the bonus when the stone was created.)

In Dungeons and Dragons

I found nothing like your DM's recollection of the limit on ioun stones in the Dungeon Master's Guide for AD&D, 2e, 3e, or 3.5e. Also silent is the Encyclopedia Magica for AD&D 2E (the game's largest magic item collection so far) in its entry on Ioun Stones (613-8). (Right after Internal Conjuration Engine but before Ipsissimo's Black Goose.)

Further, Hargenrader's Dragon #174 (Oct. 1991) Bazaar of the Bizarre column "Ioun Stones: Where Do You Go If You Want Some More?" (90-4) references the Polyhedron #15 Dispel Confusion column that seems to indicate ioun stones can increase an AD&D 2e character's ability scores not only above their racial maxima but also even above 18! Despite mentioning this unusual effect, Hargenrader's article doesn't discuss—rather surprisingly, in retrospect—the possibility of a creature employing several identical stones. (However, given the frequently punitive nature of old school D&D, this reader expects any attempt to send multiple identical stones spinning to yield explosions.)

Finally, the Encyclopedia Magica lists ioun stones as possibly either burnt out, normal, supercharged, or cursed. Inferior stones—cracked, flawed, and scorched—and resonating stones are, presumably, a Pathfinder invention so any information about a creature specifically being unable to use simultaneously both a typical stone and an otherwise identical inferior stone would have to buried even deeper within one of Pathfinder's multitudinous supplements.

Note: I also looked at Pelgrane Press's Primer of Practical Magic (2004). The book is billed as "Spells and artifacts from the Dying Earth, made available for use in [the] d20" System, and includes fifty or so additional ioun stones (some underpriced, some unbalanced, and others both—introduce them cautiously to a campaign!), but that text, too, says nothing about multiples or identicals.

  • \$\begingroup\$ Fantastic answer! Thanks for addressing the question (is there a rule that effects ioun stones in particular) with such care, rather than veering off to re-explain bonus stacking in general. Thanks again for taking a look at historical sources too. \$\endgroup\$
    – Jeff Fry
    Dec 14, 2016 at 21:23
  • \$\begingroup\$ I believe the text you quoted from Seeker of Secrets is talking about stones that can have different effects, such as those that grant a bonus on a certain skill checks (like Deep Red Sphere). This skill has to be defined by the creator, otherwise the text on the stone will make it clear that you can change it (like on Mangeta Prisms). \$\endgroup\$
    – ShadowKras
    Dec 14, 2016 at 21:50
  • \$\begingroup\$ @ShadowKras If you want to read the pale green prism ioun stone description that says, "This stone grants a +1 competence bonus on attack rolls or saving throws," as something other than "multiple possible effects…, the exact effect… determined by the item crafter when it is created," that's cool, and I appreciated your dissent. However, I'll wait to accommodate that reading until a couple of folks find that comment useful as I'm not at all sure that's a common reading, especially since another reading makes the pale green prism ioun stone's use GM-dependent. \$\endgroup\$ Dec 15, 2016 at 0:37
  • \$\begingroup\$ I stand corrected, the price of the cracked stone does match the bonus it grants (+1 * 2000 for "Save (Other)", doubled for being slotless). \$\endgroup\$
    – ShadowKras
    Dec 15, 2016 at 10:32

A bonus to a stat will stack as long as you don't have any other modifiers from items providing the same type of bonus to said stat. The only bonuses that will stack infinitely in any given situation are Circumstance bonuses, and Dodge bonuses.

If any other item provides the same type of bonus to the same stat, only the highest bonus of any type provides any bonus to said score.

So yes, you could get multiple ioun stones that boost different stats slightly, provided you weren't getting the same type of bonus anywhere else.


Typed bonuses do persistently exist since at least 3.5, when they were called Modifier Types, and the stacking rules back then are pretty much the same as today:

Different bonuses to the same statistic stack, as long as they have a different type (so a competence bonus and an insight bonus to AC stack, two competence bonuses to AC don't.)

Bonuses to different statistics always "stack", or rather apply separately to their statistics: nothing limits you from having a competence bonus on AC and one on to-hit, as long as each of these only has one competence bonus applying.

The only exception are untyped bonuses - they stack as often as they appear, as long as they have a different source. Circumstance bonuses are untyped, as are most penalties.

All bonuses of Ioun Stones are typed differently in their respective articles, depending on the type of the stone in question.

The Ioun Stones in Question do grant bonuses to different statistics, which makes the use of two of them boosting the different statistics allowable.

Even more so: You could legally fully benefit from both the normal and the flawed version of the Pale Green Prism at the same time, or you use the flawed together with two cracked stones. You can't combine the normal and the flawed though, as both grant the same typed bonuses.

For the Dusty Rose Prism, Cracked works together with the normal/flawed, however, using both normal and flawed together grants only +1 insight on AC and doesn't lift the untyped -2 on STR, as those two modifiers are on different stacks.

As a side note: nothing stops you from using several of the exact same type of Ioun Stone (for example 10 Flawed Dusty Rose Prisms), but their effects save for penalties don't stack (for effectively +1AC -20 STR). The only benefit such a massive swarm of stones might have is looking cool and being somewhat protected from having the bonus removed by shooting down the stones.


Yes. Because they are boosting different different things you are allowed to benefit from them.

  • 2
    \$\begingroup\$ I understand that this doesn't run afoul of the bonus stacking rule (as I mentioned in my question). The thing I'm looking for is if there are any ioun stone specific rules that cover this? It's not clear to me if you're saying "I'm confident no such rule exists in Pathfinder"...or if you're just speaking to non-stacking bonuses generally? \$\endgroup\$
    – Jeff Fry
    Dec 14, 2016 at 0:18
  • \$\begingroup\$ I was speaking about the bonuses themselves specifically. When I looked at the Ioun stone rules, the only thing that was special was when wayfinders were being used. Since no other rules were present I concluded that normal stacking rules were still the thing. \$\endgroup\$
    – Fering
    Dec 14, 2016 at 3:13

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