The HUD functions are organised as follows:

HUD Buttons

I. The Cast Bar

The Cast Bar appears when you touch that little button above the HUD’s badge. That button is available even when the HUD is hidden/minimised.

The buttons work slightly differently.

I.I. Spells, Potions, and Transfig

When you click any of the first three buttons, you can type in the name of the thing you want to do (Levitation Charm, Colour-Changing Charm, Antidote to Common Posions, etc) or the incantation of it in case it’s a magic (Wingardium Leviosa, Collovaria, etc). You can also type the name/incantation only partially (like “levi” or “col” or “anti”) and the HUD will find the appropriate spell; it will pick the first one in case there are multiple ones that fit the criterion (such as Lumos vs. Lumos Solem).

Upon submitting, the HUD will tell you whether you succeeded or not at casting that spell/transfiguration or brewing that potion, and your titler will change to reflect that.

If you’re a sixth-year or above, when you submit a spell/transfig you will also have the possibility of casting them nonverbally.

I.II. Herbology and CoMC

In Herbology and CoMC, you have two different consecutive rolls. First, you need to choose which plant/creature you wish to identify:

When you submit, you will perform the id roll, which will determine whether you correctly recognised that creature/plant for what it was.

Then, if you succeed at identifying a plant/creature, the HUD will prompt you for a further roll, to care for it.

If you fail at identifying the creature/plant, you will not be prompted for the care roll.

I.III. Arcane

Arcane is a catch-all skill for arcane knowledge, such as Divinations, Ancient Runes, or Alchemy. Unlike the other skills, it doesn’t have a specific target such as a single rune or anything, but rather “ranges” of targets, identified with letters of the Hebrew alphabet. When your Professor tells you to roll Arcane for their subject, they will also tell you what range counts as a success. For example, if to correctly draw a certain Alchemical Circle you need to roll a He in Arcane, you will click the button and type “He” in the text box:

As usual, the HUD will tell you whether you succeeded or failed. If you leave the text box blank and submit it, the HUD will only tell you what your target roll was.

Cheat Sheet: In order from lowest to highest, the possible Arcane rolls and the levels they’re equivalent to are:

RollMin LevelMax Level

These levels are organised in such a way that if you’re the min level for a Roll, it will be hard for you to roll that, and if you’re the max level, it will be easy. If you’re below the min level, you will have a very hard time indeed rolling that, and if you’re above the max level, that should be par for the course.

Rolling a Taw is always a critical failure, and rolling an Aleph is always a resounding success.

I.IV. Dodge

It’s pretty much exactly what it says on the tin. Since most of the time you’ll be using Dodge will be when dueling, the next section will be more relevant. When you click this button, your HUD will simply tell you whether you succeeded at dodging or failed.

IMPORTANT: Remember that each roll must be described in a post. Whether you succeed or fail, when you roll to do anything you should post to describe your actions before attempting to roll again. That means that you need to roleplay each single failure individually before you’re allowed to try to do something again (and each success, though this is less relevant). The only exceptions are for CoMC and Herbology, where both identify and care count as a single roll, and Dueling (explained below), where Defense and Attack must be explained in a single post.

P.S.: For more inconsequential/casual posts where you know other people won’t react to each individual roll of yours, it can be okay to conflate multiple rolls in a single post. However, if you do, you must describe each roll separately, so if you failed 3 times before succeeding at a spell, you must describe each failure individually and not mix them all saying “so-and-so failed 3 times then succeeded.”

II. Duelling

When you click the “Duel” option of the Main Menu, you’ll be prompted with a list of people nearby you can challenge to a duel.

They will receive a dialog box asking if they want to duel against you, and if they accept you will receive a confirmation in local.

The HUD will decide who will have the first turn (i.e. it is neither always the challenger nor always the challenged), and you can choose one of three buttons from the Cast Bar for offense: Spells, Transfig, and Dodge. If you choose one of the first two, you choose something you wish to cast offensively; if you choose Dodge, you will attempt to physically brawl against the other person as opposed to use magic.

If you try to click another skill while you’re in a duel, you will be told you can’t use it.

Once you choose your attack, you will receive a message confirming what you used and asking you to post your attack.

Once you post, they will be told about it, and will be prompted to choose a defence.

After they pick their defense, the HUD will tell you both privately whether the defense was successful or the attack was. Then, before the other person posts anything, they must pick an attack.

After both defense and attack have been chosen, the player will type their post starting with a description of how they defended and then explaining what they used to attack, and after their post you will be prompted to pick a defense, or try to Dodge.

Rinse and repeat. At any point, either of you can touch the Main Menu and click “Duel” again to end the duel.

Cheat Sheet: Dueling always takes the same basic format of Defend-Attack-Post. The algorithm is:

  1. Challenge someone to duel.
  2. First player picks an attack.
  3. Player posts their attack, and passes turn.
  4. Next player picks a defense.
  5. If the duel can’t continue (i.e. that player lost), post their failed defense and end duel. Otherwise, continue.
  6. Player picks an attack.
  7. Player posts both defense and attack, and passes their turn, i.e. they must not post immediately after defending unless they’re ending the duel.
  8. Return to step 4.


  • Spells can’t be the target of other spells. One beam hitting another is an exceedingly rare thing and when it happens the spell mostly cancel each other out. But in any case, for the purposes of MM, it can’t happen.
  • When you cast a spell, there are two tests it must pass: first, it must be cast successfully; then, it must do its job. Your HUD will tell you if you failed to cast a spell; if it doesn’t say anything, then the casting succeeded. For example, if you use Fumos as a defense, you might fail at casting it, and the HUD will tell you if that’s the case, saying something like “You failed to cast your spell!”; however, even if you succeed at casting it, it might not be enough to defend, and the HUD will say you couldn’t defend yourself (not that you couldn’t cast). These are then two separate things that are treated differently by the HUD and should be treated differently by the RP. In the former case, the Fumos casting never worked in the first place, so there’s no smoke; in the latter, there is smoke, but it wasn’t enough to serve as a defense.
  • The Dueling System is an aid to duel, but the focus is the RP. While any magic can be chosen both as offense or defense, it has to make sense within the RP of the duel. You can use a Finite Incantatem defensively by dispelling a flock of enchanted birds that were sent your way, but you can’t use it to stop an Expelliarmus on its way. The RP comes first, so before anything you decide how you’ll act within the constraints of canonicity and only then do you make the HUD roll. Be creative! But be “realistic.” Spells can do only what they can do, and no more.