Is there a particular reason your starting point for the xag-ya was the 3e version and not the D&D Next version? As an aside, I suspect we'll get an official xag-ya in Quests from the Infinite Staircase.
Well, the first reason is that I forgot all about the Next version.
However, that version doesn't really do it for me- it does lightning damage, for one thing, where my version does radiant. There's a different energon type for lightning!
Yeah, the take on them from the 3e Planar Handbook really hit the notes for me... Here's my take on them:
ENERGON
Source: 1e
Monster Manual 2, 3e
Planar Handbook.
Energons are strange creatures that embody different forms of energy. There are many types of energon, but even the best-known is rarely encountered unless bound as a guardian by ritual. However, it is very difficult to control an energon once it is summoned, so wise wizards and clerics set traps to summon these creatures when the summoner is not around to see the results.
An energon appears as a ball of energy with four long tentacles trailing out of it. Depending on the type of energon, it might crackle with electricity, rumble with thunder, radiate cold, etc.
Opposites Attract. When certain types of energon recognize one another, they immediately rush to attack one another, coming together in a massive explosion that destroys the energons. For example, a xag-ya and a xeg-yi will rush each other, as will a xac-yel and a xor-yost. Such an explosion deals damage equal to the combined death throes of both energons.
True Energons. Only the xag-ya and xeg-yi appear to be true energons; all other types may be constructed as emulations of them, for only the xag-ya and xeg-yi have ever been found in the wilds of their home planes (the Positive and Negative Energy Planes). Though the origin of other types is uncertain, they can't always be permanently banished, so at least some of them are clearly native to the World.
In addition, the strange creatures known as
aoas are hypothesized by some scholars to be a sort of negative or anti-energon.
Energon Treasure. Energons never collect treasure, but are sometimes set as guardians of other creatures' treasure.
Among the various types of energon are the following.
XAC-YEL
A xac-yel is made of fire. Its attacks do fire damage, and it is immune to fire and vulnerable to cold damage.
XAC-YIJ
A xac-yij is made of acid. Its attacks do acid damage, and it is immune to acid damage.
XAG-YA
One of the only two types of energon known to be native to other planes, the xag-ya is made of radiant energy and is native to the Positive Energy Plane. Its attacks do radiant damage, and it is immune to radiant and vulnerable to necrotic damage.
XAP-YAUP
A xap-yaup is a living ball of lightning. Its attacks do lightning damage, and it is immune to lightning damage.
XEG-YI
The negative counterpart of the xag-ya, a xeg-yi is a blot of necrotic energy. Its attacks deal necrotic damage and it is immune to necrotic and vulnerable to radiant damage.
XONG-YONG
A xong-yong is a ball of living thunder that rolls and booms constantly. Its attacks do thunder damage, and it is immune to thunder damage.
XOR-YOST
A xor-yost is formed of cold energy. Its attacks deal cold damage, and it is immune to cold and vulnerable to fire damage.
Energon
Medium Celestial, always neutral
Armor Class13
Hit Points43 (5d8+20)
Speed fly25 ft.
STR 17 (+3), DEX 17 (+3),CON 18 (+4),
INT 7 (-2), WIS 10 (+0),CHA 18 (+4)
Damage Vulnerability varies based on the type of energon
Damage Resistance bludgeoning, piercing, and slashing
Damage Immunities varies based on the type of energon
Condition Immunities prone
Senses darkvision 60 ft., passive Perception 10
Languages-
Challenge 3(700 xp)
Prof +2
Death Throes. When the energon falls to 0 hit points, it explodes in a 15' radius sphere. Each creature in the sphere must make a DC 14 Dexterity save,suffering 22 (4d10) damage of a type based on the type of energon on a failure or half that on a success.
Incorporeal Movement. The energon can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
ACTIONS
Tentacles.
Melee Weapon Attack:+5 to hit, reach 5ft., one target.
Hit:12 (2d8+3) damage of a type based on the type of energon.
Energy Ray. Ranged Spell Attack: +6 to hit, range 30 ft., one target.
Hit:13 (3d8) damage of a type based on the type of energon.
REACTIONS
Bloodied Shift. When the energon becomes bloodied, it moves 5’ without provoking opportunity attacks.
Energon Overcharge
An energon overcharge uses the Energon stat block with the following changes.
- It is Large.
- It has 190 hit points (20d10+80 Hit Dice).
- Its Death Throes trait affects a 20' radius sphere, has a save DC of 16, and deals 66 (12d10) damage on a failed save.
- Its Tentacles are +7 to hit and deal 30 (6d8+3) damage.
- Its Energy Ray is +8 to hit and deals 33 (6d10) damage.
- Its Challenge Rating is 9 (5,000 xp).
- Its proficiency bonus is +4.