On account of me not having posted for a while prior to tonight (things have been a little hectic what with Christmas, work and family commitments) I figured I'd offer up another little encounter you may enjoy throwing at your players. This was designed for use in a Lamentations of the Flame Princess game however this could be tweaked easily I'm sure to fit in any other system.
Night has fallen and there is a sinister chill in the air. Your adventuring has taken you through the woods and you worry it may be treacherous to go on as the darkness creeps in around you. The moonlight gives you just enough light to see the skeletal branches of trees clawing at the sky with a few dead leaves still clinging to them like rotting flesh to a corpse.
You decide to make camp for the night in a small clearing where you can bed down and a few evergreen trees may provide you some shelter. As you start to fall asleep you see the fog begin to roll in... not unusual for this time of year. You settle down for the night but your eyes widen at a nearby rustle and they search the surrounding area. You see nothing but the trees and the fog which begins to creep over you.
A pang of panic grips your chest as you realise you are unable to move, unable to make a sound even. You notice from the corner of your eye a tree, slithering along on its roots toward you slowly. It seems to bend down toward you as a long spindly branch moves to your mouth, prying apart your lips and forcing itself into your mouth. The rough bark splinters at your throat as you choke on it, or at least it feels as though you would. You feel a hot burning sensation from deep down your throat and the branch is removed. You can breathe once more. The tree slithers away while you are left, throat raw, still unable to move, scream, cry out or even comprehend what has just happened to you. After all, tree's don't move...
If asleep in the woods at night time on a full moon the tree spirits will attempt to attack you. On the 3 nights of the full moon they come alive and emit a paralysing dense mist at will. Once they have some helpless victims, they will force tree limbs down their throats as they lay helpless and plant within their victims a seed of their own. The paralysing effect wears off after a few hours but the following then occurs if you have a seed inside you:
Day 1: skin begins to toughen much like bark. Permanently lose 2 from Dex but gain 2 to AC.
Day 2: skin begins to harden further and movement is now extremely difficult and much slower. Perm lose a further 3 from Dex but gain 3 to AC.
Day 3: features begin to harden over as well as you more closely resemble a tree. You are now unable to speak as your mouth is covered over in tough bark (though breathing is not a problem) and roots sprout from what used to be your feet securing you to the ground. You may still move your arms (branches) slowly but your lower body is that of a tree.
Day 4: You are a TREE. Dead for all intents and purposes but you will rise again on the next full moon and be compelled to procreate as a tree spirit yourself.
The only cure for this is to drink the sap of one of these tree spirits which will make you vomit and take the seedling with it. Any transformation up to this point remains but you will not transform further. This cannot be cured by dispel magic or any other means.