What does Psionic Mastery actually do?

Question

This is part of the Psionic Mastery description from the Unearthed Arcana Mystic rules:

Beginning at 11th level, your mastery of psionic energy allows you to push your mind beyond its normal limits. As an action, you gain 9 special psi points that you can spend only on disciplines that require an action or a bonus action to use. You can use all 9 points on one discipline, or you can spread them across multiple disciplines. You can’t also spend your normal psi points on these disciplines; you can spend only the special points gained from this feature.

I think this explanation is lacking, and I didn't find clarifications around.

When I use my action to activate this new type of psi points, do I also choose the disciplines I want, and they take effect altogether? Or do I need one turn to activate this ability and then another turn to use one discipline, etc. until I finish this pool? Finally, Disciplines are a block of several options, what does it mean when I choose to use these bonus points; is the entire block unaccessible with regular psi points?

Answer 1

As Unearthed Arcana rules, this writing is a bit unpolished. Here's how I understand it:

You spend your action and gain the psi points; that's all you get from that action (the rule says you gain points that you "can" spend, not that you gain points and spend them). Those psi points are tracked separately from your normal pool.

Whenever you use a discipline later to create an effect, you choose whether to spend your normal psi points or your special psi points on that effect. You can't mix and match for a single use of an effect, but I see no rule that prohibits spending special psi points on one effect and then spending normal psi points on an effect from the same discipline.

If one were to interpret the rules to say that using special points locked a discipline from being available via normal points, there would need to be some rule that explained when that lock expired. Since there isn't such a rule, the rule against mixing point types must only apply to a single use of an effect.

Answer 2

The key benefit of Psionic Mastery: stacking of concentration effects

If you take the action to gain those extra point above and beyond your Psi Point budget, you are able to use a bonus action in that turn, but not another action. That means you may not be done for that turn.

Example

Turn 1:
Take an action to add those 9 bonus points, and on the same turn take the bonus action to Begin concentration on Truesight. (p. 27 UA Mystic Class).

Turn 2:
As an action, begin concentrating on Phantom Foe (p. 25) to confront the creature you detected with Truesight in the previous turn.

This stacking of concentration is a significant benefit: the general rule in 5e is that concentrating on another spell/magical/feature effect ends the previous Concentration.

More stacking

On Turn 3, you could (for example) begin concentrating on Distracting Haze (p. 24), but only at the 3 point level (it can use up to 7 points). All three effects would be up for the next 8 rounds, by which time you have hopefully resolved the encounter.

Note that doing the above would consume your whole bonus pool for that day, but that's an example of how to make that stacking effect work - and you will have spent none of your usual Psi Point budget.

All of the above presumes that the character has the Third Eye, Psychic Phantoms, and Psychic Disruption Disciplines. It also assumes a level 11 Mystic (Psi Points of 64, Bonus Points 9 from Psionic Mastery).

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Caveat: this answer is only for the UA rules published on 13 March 2017, which is at best unfinished and more or less in a play test level of completion. If the Mystic Class ever gets published, and this feature is part of it, review of the final form of this answer may be overtaken by events/changes based on playtest feedback.