Aasimar
Aasimar are a player character race in Dungeons & Dragons editions 2, 3, 3.5, and 5 (via the DMG and Volo's Guide to Monsters) and in Pathfinder. They are counterparts to Tieflings and Genasi, being mortals who bear the blood of Celestials - the residents of the Upper Planes - in their lineage.
Aasimar originated in the Planescape setting, as with their counterparts. Like the genasi, though, they came after the setting was initially released; the corebook for Planescape introduced only the tiefling, githzerai, and bariaur races. Instead, Aasimar had to wait until the Planeswalker's Handbook to get their first entry into the D&D world as a playable race. Aasimar are basically tailor made for people who want to play the various Good branches of the Alignment tree, especially as Clerics or Paladins, since they literally have living good in their veins, though, as with tieflings, playing around with the concept was popular.
Unlike tieflings, aasimar variability wasn't given a lot of attention. There was some afterthought mentioning of alternate stat bonuses and spell-like abilities in lieu of resistances, but it wasn't until "Warriors of Heaven" that they got similar diversity charts to the tieflings.
In 4e, aasimar never made it over. Instead, they got replaced with devas, former angels banished or voluntarily departed from the Astral Sea to live amongst mortals. The explanation given was that having three races who all shared the same basic origin of "a horny Outer Planar decided to get itself some sweet Prime Worlder poontang" was a little silly, and reeked of gridfilling - the "we have X already, so we need Y and Z to contrast it". So 4e played around with the ideas; the basic idea of "being touched by good/evil/the elements" remains intact, but "cursed descendant of an empire that swore pacts with devils", "angel that abandoned heaven for the mortal world" and "escaped slave-race from the Elemental Chaos" are all pretty different origins.
In Pathfinder, it's noted that a lot of Aasimar actually tend to go evil either because superstitious yokels tend to pile on emotional trauma and guilt until they snap by constantly harassing them for "blessings" that the aasimar can't actually give, or because they realize everyone automatically expects them to be capital-G Good Guys/Girls and so they can easily manipulate people. This is yet another way in which Pathfinder likes to present itself as the GrimDark D&D equivalent setting. They can have lots of different possible starting types, depending on which kind of celestial they descended from. Interestingly, supplements explicitly encourage white-hot holy-on-unholy action by stressing the odd sense of kinship most aasimar feel for their similarly-bullshit-cultural-expectation-wracked fiend-blooded counterparts. Naturally, the Pathfinder Aasimar sourcebook, "Blood of Angels" follows the same plans as the Tiefling sourcebook "Blood of Fiends", giving a D100 table for alternative traits to replace the vanilla aasimar's spell-like ability, and racial variants for aasimar recognizably tied to one of the existing celestial races - Agathions, Angels, Archons, Azata, Garudas and Peris.
The Not-So-Legendary Aasimar Tables
As mentioned above, aasimar, like tieflings, were given a fluff as being a very mutable "bastard" race, but not the stats to back it up... at least, in their initial publication. In the relatively obscure "Warriors of Heaven" sourcebook, which also detailed the celestial races and even made PC race options out of them, the Aasimar finally received what the tieflings had back in the Planeswalker's Handbook; randomization tables. However, these were actually presented as being for aasimar NPCs and so very little attention was given to using them to customize PCs; a single sentence saying that a player could give up their default 50% resistance to heat & cold for 1 roll on the Aasimar Abilities table was all the info we were given. Of course, nothing stopped/stops a DM from simply stealing the Tiefling randomization rules (make 1d4 rolls on Appearance and give up the heat/cold resistance, saving throw bonus and magic resistance to make 5 rolls on Abilities).
Aasimar Abilities
- 01-03: Alter Self (1/day)
- 04-06: Augury (1/week)
- 07-09: Blur (1/day)
- 10-12: Comprehend Languages (1/day)
- 13-15: Detect Evil (1/day)
- 16-18: Detect Lie (1/day)
- 19-21: Detect Magic (1/day)
- 22-24: Enthrall (1/week)
- 25-27: Feather Fall (1/day)
- 28-30: Know Alignment (1/day)
- 31-33: Light (1/day)
- 34-36: Mirror Image (1/day)
- 37-39: Protection From Evil 10ft Radius (1/day)
- 40-42: Protection From Normal Missiles (1/week)
- 43-45: Read Magic (2/day)
- 46-48: Shield (1/day)
- 49-51: Strength (1/day)
- 52-54: Water Breathing (1/week)
- 55-57: Half damage from Fire
- 58-60: Half damage from Cold
- 61-63: Half damage from Electricity
- 64-66: Half damage from Acid
- 67-69: +2 to save vs. Poison
- 70-72: +2 to save vs. Fire
- 73-75: +2 to save vs. Cold
- 76-78: +2 to save vs. Electricity
- 79-81: +2 to save vs. Petriciation/Polymorph/Paralysis
- 82-84: +2 to save vs. Rod/Staff/Wand
- 85-87: +2 to save vs. Spell
- 88-93: Celestial Aura (-2 penalty to enemy attacks)
- 94-96: Immune to nonmagical weapons
- 97: Immune to energy drain attacks
- 98-99: Roll twice, rerolling results above 97
- 100: Roll three times, rerolling results above 97
Aasimar Appearance
- 01-04: Silvery skin
- 05-07: Green-tinted skin
- 08-10: Blue-tinted skin
- 11-14: Golden skin
- 15-16: Pointed ears
- 17-18: Ridged ears
- 19-20: Doglike ears
- 21-25: Angular face with high cheekbones
- 26-29: Perfect white teeth
- 30-31: Long, distinguished nose
- 32-33: Hooked nose
- 34-36: Crystal-blue eyes
- 37-39: Bright green eyes
- 40-42: Gleaming silver eyes
- 43-45: Golden eyes
- 46-48: Six fingers per hand (including thumb)
- 49-50: Fingers one inch longer than normal
- 51-52: Animal horns on head
- 53-54: Silver or gold fingernails
- 55-57: Long, slender arms
- 58-60: Long, slender legs
- 61-65: Featherd Wings (MV Fly 18 [D])
- 66-72: Vestigial wingbones on shoulders
- 73-76: Opalescent skin
- 77-80: Naturally tanned skin
- 81-83: Body covered with speckled markings
- 84-85: Bald, hairless
- 86-89: Small feathers rather than hair on 1d10x10 of body
- 90-95: Special Side Effect (roll on Side Effects table)
- 96-98: Roll twice, rerolling results above 89
- 99-00: Roll three times, rerolling results above 89
Aasimar Special Side Effects
- 01-10: Sweet, fresh odor surrounds body
- 11-15: Surrounded by an aura of calm that grants +2 to morale checks for good-aligned creatures within 30 feet
- 16-25: Heals twice as quickly
- 26-30: Susceptible to fire (+1 point of damage per die)
- 31-35: Susceptible to cold (+1 point of damage per die)
- 36-45: Presence eases animals (+4 to reactions)
- 46-50: Touch inflicts 1d4 damage to evil creatures
- 51-55: Odd skin composition gives base AC of 1d6+3
- 56-60: Takes 1d6 points of damage from a splash/vial of unholy water
- 61-70: Can be turned by evil priests
- 71-75: Can speak telepathically (range 1 mile)
- 76-80: Can leap up to 15 feet vertically or 30 feet horizontally
- 81-85: Natural (ground) movement rate of 15
- 86-90: Can't be held or ensnared, as per a free action spell
- 91-98: Can speak any language
- 99-100: Eyes have the power of true seeing (as per spell)
In 5e
Aasimar returned to 5e in the DMG as the sample race for showcasing the "build a race" rules. They're basically Tieflings flipped to a more Celestial aspect, complete with sharing the same +1 Mental Stat (Wisdom, for Aasimar) +2 Charisma bonus, Darkvision, Damage Resistance (Necrotic + Radiant) and spell-like abilities at level 1 (Lights), 3 (Lesser Restoration) and 5 (Daylight) format. They were recently voted one of the three most-popular races for a new D&D expansion to create in detail, with Mike Mearls professing they were his favorite race and that he really wanted to do them right because, in his own words, there's a tendency to make the good guys boring.
The first "official" release of the 5e aasimar didn't happen until November 2016, when they were one of the player races added in the Forgotten Realms-based "Volo's Guide to Monsters". This version takes them a good way away from the "radiant tiefling" ruleset, giving them new lore that described each aasimar has a celestial guide or deva who speaks to them through dreams, exhorting them to do good... often in a very harsh and inflexible way. They have three subraces, that gain special abilities at third level: the Protector aasimar, who gets +1 Wisdom and can sprout wings and fly around dealing extra radiant damage on their spell and weapon attacks; the Scourge aasimar, who gets +1 Constitution and can turn into a living divine sunlamp that deals Radiant damage to everyone around them, including themself; and the Fallen aasimar, who, having turned to evil, gets +1 Strength, causes fear in others, and deals Necrotic damage instead.
As a handy tip for DMs, anyone who wants to play a Protector instead of a Scourge is a wimp who prefers "not taking damage" to burning evil with their very gaze, and should be politely, but firmly, asked to leave. Anyone who wants to play a Fallen is probably Chaotic Stupid and should be immediately ordered to leave.