The Sorcerer's Tides of Chaos is interesting because whether or not it refreshes is left up to the DM:
Any time before you regain the use of this feature, the DM can have you roll on the Wild Magic Surge table immediately after you cast a sorcerer spell of 1st level or higher. You then regain the use of this feature. [PHB 103, emphasis added]
Are there any other features/feats/spells/etc that are left explicitly up to the DM to control?
Rule 3 is that the DM describes the results of character actions, so to some extent the DM is in control of every feature, feat, spell etc. This wiki attempts to list only those that explicitly call for the DM to determine the outcome of actions by fiat, as opposed to rolls and such. 'Downtime activities' are not currently included as these are not specifically 'features' by the question's definition, but may be requested. The original author considered only the PHB but wiki contributors may add other official sources (please attribute).
Emphases by contributor in all quotes which follow.
Cleric, Divine Intervention
Beginning at 10th level, you can call on your deity to intervene on your behalf when your need is great.
Imploring your deity’s aid requires you to use your action. Describe the assistance you seek, and roll percentile dice. If you roll a number equal to or lower than your cleric level, your deity intervenes. The DM chooses the nature of the intervention; the effect of any cleric spell or cleric domain spell would be appropriate.
Druid, wild form
Worn equipment functions as normal, but the DM decides whether it is practical for the new form to wear a piece of equipment, based on the creature’s shape and size.
Whether or not wild shaping into a new form will cure a druid of disease is up to the DM (DMG 256):
Diseases can affect any creature, and a given illness might or might not pass from one race or kind of creature to another. A plague might affect only constructs or undead, or sweep through a halfling neighborhood but leave other races untouched. What matters is the story you want to tell.
Phantom Rogue (TCoE), Tokens of the Departed:
as a reaction when a creature you can see dies within 30 feet of you, you can open your free hand and cause a Tiny trinket to appear there, a soul trinket. The DM determines the trinket’s form or has you roll on the Trinkets table in the Player’s Handbook to generate it.
- As an action, you can destroy one of your soul trinkets, no matter where it’s located. When you do so, you can ask the spirit associated with the trinket one question. The spirit appears to you and answers in a language it knew in life. It’s under no obligation to be truthful, and it answers as concisely as possible, eager to be free. The spirit knows only what it knew in life, as determined by the DM.
The DM chooses from the following possible omens:
- Weal, for good results
- Woe, for bad results
- Weal and woe, for both good and bad results
- Nothing, for results that aren't especially good or bad
At the DM's option, you may choose an alternative curse effect, but it should be no more powerful than those described above. The DM has final say on such a curse's effect.
Some typical commands and their effects follow. You might issue a command other than one described here. If you do so, the DM determines how the target behaves.
Choose one of the following options for what appears:
- One beast of challenge rating 2 or lower
- Two beasts of challenge rating 1 or lower
- Four beasts of challenge rating 1/2 or lower
- Eight beasts of challenge rating 1/4 or lower
The spell doesn't say which specific beasts you get, but designer intent is that the DM chooses from among those of the CR range specified by the caster. For other spells, Sage Advice explains that the DM makes all choices not explicitly provided to the player in the spell description. Examples include conjure celestial, conjure fey, conjure minor elementals, conjure woodland beings, and summon lesser demons.
Conjure Celestial
Cf. Conjure Animals, above.
Conjure Fey
Cf. Conjure Animals, above.
Conjure Minor Elementals
Cf. Conjure Animals, above.
Conjure Woodland Beings
Cf. Conjure Animals, above.
The GM answers each question with one word, such as "yes," "no," "maybe," "never," "irrelevant," or "unclear" (if the entity doesn't know the answer to the question). If a one-word answer would be misleading, the GM might instead offer a short phrase as an answer.
You contact your deity or a divine proxy and ask up to three questions that can be answered with a yes or no...You receive a correct answer for each question...In a case where a one-word answer could be misleading or contrary to the deity's interests, the GM might offer a short phrase as an answer instead.
You ask a single question concerning a specific goal, event, or activity to occur within 7 days. The GM offers a truthful reply. The reply might be a short phrase, a cryptic rhyme, or an omen.
This spell can have additional effects depending on the terrain in the area, as determined by the GM.
Fissures. Fissures open throughout the spell's area at the start of your next turn after you cast the spell. A total of 1d6 such fissures open in locations chosen by the GM.
the steed takes on a form that you choose: a warhorse, a pony, a camel, an elk, or a mastiff. (Your DM might allow other animals to be summoned as steeds.)
Amusingly, find greater steed does not have an 'other animals' clause, even though the default creatures available are the only difference between the spells. The dragonnel from Fizban's does have a DM option to allow it summoned via that spell, though.
Another creature might seek retribution in other ways (at the DM’s discretion), depending on the nature of your interaction with it.
You gain no special power over the creature, and it is free to act as the GM deems appropriate. It might leave, attack you, or help you.
The GM might allow you to choose different targets. For example, if you transform a bee, its giant version might have the same statistics as a giant wasp.
Second, you can bind an extra effect to the area. Choose the effect from the following list, or choose an effect offered by the GM.
Infernal Calling (XGtE)
The devil is unfriendly toward you and your companions. Roll initiative for the devil, which has its own turns. It is under the Dungeon Master’s control and acts according to its nature on each of its turns, which might result in its attacking you if it thinks it can prevail, or trying to tempt you to undertake an evil act in exchange for limited service.
If you know a specific creature's name, you can speak that name when you cast this spell to request that creature, though you might get a different creature anyway (DM's choice).
When you transform, you choose whether your equipment falls to the ground, merges into the new form, or is worn by it. Worn equipment functions as normal. The GM determines whether it is practical for the new form to wear a piece of equipment, based on the creature's shape and size.
For the effects of shapechange on disease, cf. wild shape, above.
Summon Lesser Demons (XGtE)
Cf. Conjure Animals, above.
An insane creature can't take actions, can't understand what other creatures say, can't read, and speaks only in gibberish. The DM controls its movement, which is erratic.
When you first gain the ability to cast this spell, you learn the sigil sequences for two destinations on the Material Plane, determined by the GM.
You might be able to achieve something beyond the scope of the above examples. State your wish to the GM as precisely as possible. The GM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong.
When you cast the spell, you change the current weather conditions, which are determined by the DM based on the climate and season.
Although this appears to be chosen by the DM, note that DMG 109 includes a random table for weather.
Reincarnate
The DM may roll on a random table or simply choose the new form.
