↠ You describe his canon point as arriving through a teleporter. All rifters are required to arrive via a dream—so he can dream he stepped through a teleporter, or take a nap next to one or something like that, but must arrive from sleep.

↠ Rifters aren't able to learn native magic, though they may find that studying how native mages work can help them access their own magic more comfortably.

↠ While he can't learn native magic, he can potentially learn additional spells from his canon beyond what's described in your app via applying for a canon update and/or specialization purchase. Characters each have three specialization "slots" by default; in his case, since his abilities are already pretty diverse and useful compared to native characters', he'll have two slots remaining. If you reach a point where you're interested in adding magic via a specialization, feel free to contact us if you have questions about it!

↠ The general limits you describe on overall magic use are appropriate (and about the same as those for native mages): he'll have a finite reserve of energy to cast spells and attempting to push past it will risk damaging his health or worse (and generally be ineffective). Bigger spells will use up more energy. Expending a lot of energy at once, whether by doing several big spells in a short period of time or using smaller doses of magic consistently throughout the day, will deplete his energy and he'll require rest to recharge. We're not going to put a D&D-style "you can do X spells per day" type cap, just ask that you keep Allumin's power levels roughly on par with those of natives, so if he's ever running circles around native characters in a thread/plot/situation and doing most of the problem-solving, that means he's doing too much.

↠ As you correctly noted, all of his abilities (unless we specifically noted otherwise here) will have line of sight limitations. They will also be vulnerable to Templar abilities, magebane, and anti-magic spells/enchantments.

↠ He can keep Misty Step, which will function like DA's Fade Step just with some added mist.

↠ Mage Armor, like real armor, will eventually break if subjected to enough damage and so isn't guaranteed to last for a full 8 hours no matter what. We think that's probably already what you had in mind, but just in case.

↠ He can keep Alarm! But it will be expensive, like you said, (especially on a Riftwatch salary) and once he's outside the city of Kirkwall or a roughly equivalent distance out to sea the signal will no longer be able to reach him to let him know if the alarm is tripped.

↠ Alter Self will not be able to change his face or voice (or make his elf ears look human), but he can grow gills/claws/etc. as described. Once he does alter his form, it will last an hour and he won't be able to revert to normal until that hour elapses.

↠ Gaseous Form will have the same sort of time nerf: anyone turned to mist will remain mist for an hour whether they like it or not.

↠ Disguise Self will have a time limit of at most 15 minutes per use, decreasing from 15 depending on the complexity of the illusion.

↠ The line of sight limitation will include his Sending spell—so he can use it to communicate with someone across a room, but not across the continent—and he'll only be able to use it 3 times per day.

↠ His Mending ability will always have a chance of not working on a given object, no matter how many times he tries, for no apparent reason. (Just in case we need something to be broken for plot reasons, or players prefer to make their characters deal with something remaining broken even though he's standing right there, etc.)

↠ Detect Magic will only work when something/someone is actively using magical energy. He won’t be able to use it to identify mages if they aren’t actively casting, possessed beings who aren't using magic, or enchanted objects if the enchantment is dormant. Anchors, however, will always have a slight aura. Determining what kind of magic is in use will be limited to a vague sense of the 'school' of magic at work (e.g., 'elemental' or 'creation' or 'blood magic') not the specific nature of the spell, and this will require him to spend time gaining familiarity with the nature of magic in Thedas and re-learning how to identify it, since it won't necessarily resemble the magic he's used to. Similarly, while Identify will be able to detect magic currently in action (regardless of whether it'd be classified as an active or passive spell by DA terms), it will take practice to be able to recognize the general type of magic at work. He will not be able to determine what magical artifacts do or how they work.

↠ Fabricate will be nerfed entirely.

↠ His wand won't be entirely bricked, but it will only do weakened versions of his cantrips. To do fully-powered versions or any of his more significant magic that would usually require a wand, he'll need to acquire and learn to use a staff.

↠ Like native elves, he'll be able to see in the dark—but more like a cat than as if the area is brightly lit, and his eyes will reflect light in the dark. He'll also lose all of the inherent resistances to magic elves have in his homeworld. But it's fine for him to be tall!