“What dangers he might meet he could not know, so he selected three spells of general application: the Excellent Prismatic Spray, Phandaal’s Mantle of Stealth, and the Spell of the Slow Hour.” – Dying Earth
Spells and magic items from UA are in play.
The spell acquired by a magic-user upon gaining a new level is chosen by the magic-user. However, the spell must be of a level the magic-user is capable of casting at their new level and the regular “chance to know” roll must be made. If the roll fails, another spell can be chosen until one succeeds.
Spells containing a person's name in the spell title (e.g. Tenser's floating disc) cannot be chosen at any time – they must be found “in the world”, through adventure.1)
When creating a new character, magic-users and illusionists should only roll on and/or select from the spells in the PHB. On level-up, spells from UA can be selected.2)
Magic resistance applies to all spells, not just to magic-user spells.
Touch spells with the duration of “one touch” can be held in-hand until something is touched. If the character touches themselves or one of their items with that hand, the spell goes off. Be careful.
A full night’s rest is not necessarily needed to recover spells. Only the amount of time dictated by DMG 40 is required. This means a two full suites of 1st level spells could be easily cast by someone with a day to spare.
If a non-offensive spell is used offensively, such as teleport, the unwilling target is entitled to a save vs spells, and typically will need to be touched for the spell to target them.
While most spells do stack, spells of the same line do not. Only the best benefits from each spell are used. The classic example is bless, chant, and prayer.
There is no special mechanic for this in AD&D; it usually works like a regular melee attack vs the target’s AC.
Shocking grasp and some other lightning-based effects ignore metal armor and metal shields (but not their plusses).
If the target is significantly larger than the person trying to touch them, the DM may assign some bonus to the to-hit roll, such as +2 for a human trying to touch an ogre, or +4 to touch a giant, or +6 to touch an adult dragon.Ex
Saves to disbelieve illusions benefit from any wisdom-based mental save modifier.
Scroll fading rules kick in if the scroll is taken from the place it was discovered in. Being sealed inside a container does not matter, even if the container was never opened. Merely looking at a scroll’s contents (and therefore triggering any curses) is sufficient to reduce the chance of fading to zero. Any class can do this, and read magic is not required.
Attempting to know a spell via a scroll releases the magic from the scroll. Whether the to-know attempt fails or succeeds, the writing fades from the scroll.3)
A reaction roll can be used to determine the sword’s initial disposition to its possessor. It may be helpful and inform its owner of its powers. It is able to use its powers on its own if it feels like it.
Magic circles of protection can be drawn without the use of a spell.4) The production and nature of these circles are presently left up to the DM for their own campaign, as no player has ever attempted this in ours. But we'll put a TODO here as something we could set up some rules for in the future.
The new types of plate armor made available in UA (bronze, field, full) are only available as magic items.Ex6)