OSR Parasite

PARASITE Draft 0.1
HD: As host +2HP
Saves: As host +special
Advancement: As Fighter
Attack: As host

You are a vicious and deadly parasite, that leaves a trail of corpses in your wake. You puppet the creatures you enter.

PARASITE LIFE
Parasites are a collective of impossibly tiny living creatures who act as one whole towards a unified goal and are perfectly in cooperation. They have no true body of their own, but inhabit and spread through every inch of creatures they live inside called hosts. Parasites come in two forms, muscles parasites, who feed the muscles tissue by leaching the brain, or brain parasites who wither away bodily tissues to increase mental capabilities. Muscle parasites gain a +1 bonus to saves against poison. Brain parasites gain a +1 bonus to saves against spells. All parasites can sense other parasites within 10ft of them. Only one parasite can inhabit a host at a time.

HOST BODY
You do not roll ability scores as per normal, instead you take on the ability scores of your host creature you are inhabiting at the time. You and your host pool HP into one shared sum. Whether you are a brain or muscle parasite, you functionally control the entirety of the creature you inhabit. You gain the features and ability of whatever you are controlling, be it a bear's mutliattack, or a MU's spell casting. If your HP depletes you and your host die.

Whenever you advance in level and you are a muscle parasite, decrease one of the mental ability scores (INT WIS CHA) by one point and increase one of your physical ability scores (STR DEX CON). If you are a brain parasite reduce a physical ability score and increase a mental score instead. If an ability score ever goes below 5 the host is no longer healthy enough to carry you and you must find a new host in [Level] days, or they die.

DEAD HOSTS AND NEW HOSTS
If your hosts dies but you do not, are you immobile in the lifeless body. Getting inside a new host requires touching a living target and combative roll, if you are a muscle parasite you and the target roll 1d20+your middlest physical ability score (rolls add the middlest mental score if you are a brain parasite). You gain Advantage if your target is eating your current host. If the target fails you are inside of them but do not have control yet. After their next rest you and the target repeat the commutative roll, if they fail you gain control of them, and they are your new host. If you fail the body has fought you off and you have [LEVEL] days to find a new host.

TELLS
You leave a sign that things are not quite right with the body you inhabit.
1 Hair falling out in clumps
2 Glassy eyes
3 Black blood veins visible under the skin
4 Putrid rotting breath
5 A wet, rattling, and pervasive cough
6 Shaky hands and face

STARTING HOST
At first level you are inside of a 1HD creature, this may or may not entail some presumed starting equipment.
1. Human or Demi-Human
2. Giant Beetle
3. Goblin
4. Pixie
5. Giant Shrew
6. Spitting cobra