Shapechanger - When on less than 25HP, it can choose to turn into a Yuan-Ti Abomination (in Snake Form without the ability to change back). However, the new creature hs the same HP as the old Type 4 had.

Form - A typical Yuan-Ti Malison Type 1 (however extremely strong), with a 15ft tail typical of a Yuan-Ti Abomination. It is 10ft tall and weighs 200lbs fully grown. It also has acidic blood as well as a gland where poison is secreted to coat weapons in. The tail has AC 19 and 63 HP of the monster.

Usually is a highest level bodyguard to a Yuan-Ti Abomination, however occasionaly this creature may attempt to overthrow an Abomination.

Can only be created by breeding a Yuan-Ti Malison Type 1 and a Yuan-Ti Abomination with the Yuan-Ti Abomination birthing it (usually the end master). These creatures are infertile (whilst they still do have sex organs). Unless it injures a snake it is friends with all (and can talk to them).

Maturity - On birth (from an egg) is a juvenile Guard. After 2 weeks, it is a lesser Guard and after 6 weeks it is fully grown.

Juvenile - No poison secretion gland for weapons. 7ft tall, 10ft tail, 30ft speed. NO multi attack and constriction has one target. Poison damage - Bite does 1d4, Scimitar does none (and is formed in the egg) and the Barbs do 1d12. Can be magically charmed and can be prone. HP 100 AC 16 CR 8

Lesser - No poison secretion gland for weapons. 8ft tall, 12ft tail, 40ft speed. Multi attack - 2 melee, one Barbs and one melee or one constriction. Poison damage - Bite does 1d8, Scimitar does nothing and Constriction does 2d8. It can constrict two targets and escape DC is 15 dexterity. It can be prone. HP 125 AC 17 CR 9

Multiattack - The Yuan-Ti makes two melee attacks, one constriction of two, one constriction of one and one bite attack on that same creature, or one barb damge on a constricted creature and one bite attack on another creature in it's grip. The Yuan-Ti cannot move if it uses the multiattack.

Bite - Melee Weapon Attack: +5 to hit, reach 6ft, one creature. Hit: 1d8 + 5 piercing damage plus 2d8 poison damage.

Scimitar - Melee Weapon Attack: +6 to hit, reach 7ft, one creature. Hit: 2d4 + 3 slashing damage plus 1d10 poison damage.

Constrict - Melee Weapon Attack: +7 to hit, reach (tail length) 10ft, two creatures (max). Hit: 2d8 + 4 bludgeoning damage as well as Barbs in tail deal 2d8 + 5 piercing (+7 to hit the first time, guaranteed on the second time) plus 2d12 poison. The target(s) are then grappled (DC escape 16, must succeed on both dexterity and strength (due to STR 19 on the tail)). Until the grapple ends, the Yuan-Ti cannot use it's tail to constrict any more victims.

Tail whip - +4 to hit, reach the length of the tail - 2ft. Deals 2d6 bludgeoning damage and on a successful DC 17 ability check deals 2d12 poison and counts as one round of poisoning.

Tail lash - If a creature comes within the length of the tail - 2ft of the Guard with no active constriction and with no attempts to sneak, roll a d20. On 1-13 the snake does nothing. On 14-19 it bludgeons the creature with +4 to hit and it deals 1d8 damage. On a critical 20 it constricts the creature and uses change on it.

Change (only applicable if has been blessed by a Yuan-Ti Abomination) - If a creature wants this to be done, they can tell the DM and walk up to the Guard, and the Guard then uses a special bite attack that only  deals 1d2 damage (this can be done at any time). The player then becomes a juvenile Yuan-Ti slave. After 1 long rest it becomes a full Yuan-Ti slave. Also, if a creature has been in the constriction of the Guard for at least 3 rounds not necessarily one after another, the Guard has injected enough venom for there to be no choice. If blessed, ANY level of Guard can change a creature.

New stats Juvenile - all stats if not already higher go to the stats of a Yuan-Ti Guard - 1. The change takes 30s. The height increases by 3ft and the creature becomes large. A tail that is the creatures height * 1.4 sprouts. The character has the choice of having a tail and legs (speed 35ft) or just a tail and no legs (speed 45ft). All lower body armour falls off broken. The creature then has serpentine eyes and a forked tongue. AC 19 HP 3d12 + their new CON modifier. Can not be poisoned.

New stats full - All ability scores are themselves plus 1. The tail increases length by the creatures height * 1.1 (if no legs, height is equal to the length of the tail plus the height of the torso and head). HP = 6d12 + their new CON ability score. The head is now a snake head (such as a Yuan-Ti Malison Type 1) and the creature now has the ability to smell all humanoids within a 40ft range. You can bite and constrict like a Yuan-Ti Guard but can only change others if blessed by a Yuan-Ti Abomination. Cannot be poisoned or prone.

Saving throws - To stop the transformation (rolled immediately and before every long rest until a full transformation) is a DC 18 CON saving throw. A failure is a transformation and a success is a transformation into a Yuan-Ti Half. To stop alignment changes is a DC 17 WIS saving throw. A failure results in alignment change to that of the Guard and possible DM Control if the character is unwilling to fight their own party. Even if the first throw is a success, the second throw is still has to be carried out.

Yuan-Ti Half - A 2ft tail sprouts. HP plus equals 2d10. Snake eyes and teeth, and a 1ft height increase. Patches of reptilian skin come into random places. It cannot tail whip or tail lash.

Universal results of Race Change into a Yuan-Ti - If not already learnt you gain knowledge of Abyssal and Draconic as well as how to use (and or hide) a tail. You can shape change temporarily into a snake half your height, losing all weapons and armour as they had as it falls off. In the snake form you can only constrict and bite (full as Yuan-Ti Juvenile or full but no modifier if Yuan-Ti half), one target. A poison gland also appears at a place of the characters choice. Unless it injures a snake it is friends with all (and can talk to them).