The Council of Wyrms campaign setting offered as a character option the half-dragon, a crossbreed of a demihuman and a dragon with natural shapechanging ability. Limited to half-gold, half-silver, and half-bronze in the campaign setting (as the dragons there were limited to the metallic, gem, and chromatic dragons). In Dragon Magazine #206, the options were expanded to Krynnish half-silvers, half-chiang lung, half-shen lung, half-Greyhawks, half-steels, half-deeps (aka Drow-Dragons), and half-irons. However, there were a handful of dragons left out of the selections, including the half-adamtite and half-radiant. Both were specifically left out of the selection for different reasons, but I was never satisfied with those reasons. Presented here is my take on the Half-Radiant Dragon, rare even compared to other half-dragons. See the Council of Wyrms set or issue #206 of Dragon Magazine for details on how fixed and discretionary abilities operate.
Appearance: Normal half-dragon with pearly-white hair, lustrous white irises, pale skin with shimmering flecks.
Ability-score modifiers: +1 Strength, +1 Dexterity, –1 Wisdom, –1 Charisma.
Ability-score ranges: Str 6/19, Dex 6/19, Con 5/18, Int 3/18, Wis 3/17, Cha 3/17.
Alignment tendency: Any.
Allowable classes: Cleric/priest (14), fighter (10), mage (10), specialist—invoker (14), specialist—force mage (14), thief (11).
Discretionary abilities: Create/destroy air (1/day), Bigby’s interposing hand (1/day), Bigby’s grasping hand (1/day), wall of force (1/day), forcecage (1/day), dragon fear (once per day).
Fixed abilities: Claw attacks (1d6/1d6), breath weapon (pulses of magical force to a 20 foot range, 3d6 damage, usable twice per day; pulses can be divided between up to 3 targets. Successful save vs. breath for no damage.).
Average Height and Weight: Height: 78/74 + 2d8. Weight: 120/100 + 3d8.
Age: Starting age: 14 + 1d4 years. Maximum Age Range: 300 + 3d20. Middle Age: 150 years. Old Age: 200 years. Venerable: 300 years.
Thieving Skill Adjustments: PP —, OL –10%, F/RT –5%, MS +5%, HS +10%, DN +5%, CW —, RL +5%.
This might be covered on the CoW rules, but what multiclassing options are allowed for half-radiant dragon characters?
None at all. Half-dragons cannot be multiclassed or dual-classed.