For Abilities, declare what you're attempting, and roll a D20 (
Online dice rollers here, I used Tira Dadi). I then post the result of what you attempted.
For Combat, Declare what weapon/spell you're using, and roll D20 with relavent modifiers, and relavent damage dice together. then as above I make a larger post for the whole combat encapsulating three rounds (Three Rounds Rapid)
Sleep doesn't incur any saves. It simply renders the weakest unconcious for 60seconds. I've house ruled you can wake yourselves up with a D20 roll before your would make an attack for your turn, but party mates can use an action with no roll to wake you up.
Sleep
1st-level enchantment
Casting Time: 1 action
Range: 90 feet
Components: V, S, M (a pinch o f fine sand, rose petals,
or a cricket)
Duration: 1 minute
This spell sends creatures into a magical slumber.
Roll 5d8; the total is how many hit points of creatures this spell can affect. Creatures within 20 feet of a point you choose within range are affected in ascending order of their current hit points (ignoring unconscious creatures).
Starting with the creature that has the lowest current hit points, each creature affected by this spell falls unconscious until the spell ends, the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake. Subtract each creature’s hit points from the total before moving on to the creature with the next lowest hit points. A creature’s hit points must be equal to or less than the remaining total for that creature to be affected.
With regards to (dis)advantage, it is indeed two dice for the relavent roll, picking highest for advantage, and lowest when at disadvantage.
Advantage and Disadvantage
Sometimes a special ability or spell tells you that you have advantage or disadvantage on an ability check, a saving throw, or an attack roll. When that happens, you roll a second d20 when you make the roll. Use the higher of the two rolls if you have advantage, and use the lower roll if you have disadvantage. For example, if you have disadvantage and roll a 17 and a 5, you use the 5. If you instead have advantage and roll those numbers, you use the 17.
If multiple situations affect a roll and each one grants advantage or imposes disadvantage on it, you don’t roll more than one additional d20. If two favorable situations grant advantage, for example, you still roll only one additional d20.
[Quick edit]
Nyx being a Rock Troll only confers adv on the saving throws. so far as I can see it doesn't grant a saving throw. If you know which section I'm missing, point it out to me?
