Because turns happen simultaneously in the same 6 seconds, if you fire at him, even if you say pop up, fire, hide, there is a window where he can fire at you on his turn. Otherwise everyone would just carry a tower shield and be perfectly immune all the time from arrows while firing "on their turn."

This rarely comes up but this is a rule of superposition. The only strange bit is if you kill someone or knock them out, who could have shot at you on their turn, but your turn is first, then they can't fire at you as they're dying.

I feel like I need to revise this with our new understanding.

All turns happen in 6 seconds. I don't want to say you have less than that split between all enemies and you. It's not absolutely serial.

If you manage to hide, then no, they will not be able to target you effectively, though you can still be shot at. You need to know or guess at their location and have disadvantage, so enemies typically won't unless they don't have anything to lose.

Shields and cover count as 3/4 (+5AC) unless you are hidden.

If you successfully hide and run away, their chances of guessing where you are is zero. I will give them a roll within 1 square of where you last were so effectively they won't hit you. (I want to say there's always a chance but I'm biting Bear's tongue hard.)

Reactions occur after the action, so you would get first hit if you popped up, potentially downing them before they can attack unless otherwise specified.

Is there anything else I'm missing?

Seeing Alice return Yulya casts EMBOLDENING BOND on Alice and Cat.
Do not engage that beast too far from here or I cannot assist you! Ideally we would lure it here. And be on the lookout. We do not want to be the ones getting surprised and ambushed. We need to find out where they are!



[Can I cast Emboldening Bond on people I cannot see? Alice is still under the snow. And all snow counts as difficult terrain right?]

>Joy turning D&D into a real-time strategy game
I understand your intention and I'm always for making the game more realistic and interesting but in this case - just no! It's not gonna work out.

We can't throw turn-based game mechanics completely out of the window like that because it will result in a lot of unresolvable problems and unbalance things. Yet we sort of have to, because we're not sitting on a table but post independently and out of order on the internet so you have to work out an order.  I'm the last to carve out cheesy advantages for me, I play Monk not because it is easy but because it is hard. But there's a line between hard and impossible.

Tamamo said it, the Monk relies on not being hit. Not having a lower chance of being hit or striking first, but to not being able to be targeted by most enemies at all as long as cover is available. I'm Ashley-tier weak, cannot use a shield and even average enemies can one-shot me. I can't afford getting struck, neither ranged, nor in melee. My character is already one of the hardest classes to play and relies on a well-balanced game and careful planning of every step I make so I don't end up in a position where I can get hit. If every enemy can just shoot or strike me in my own turn while I race by, we can call it quits. Then I'm just a very bad melee class / clay pigeon.

So let's look at Vanilla rules, OK?
There's the 'Ready' action for that. You can ready an attack in your turn and release it in ours upon a trigger. But that needs to be declared beforehand on your turn. Also per the rules, a creature can only Ready an attack if it is aware of the trigger (me). You cannot just run around and then shoot at anyone that pops up on their turn. According to Vanilla Rules, No, you cannot attack a monk that pops up, strikes you ranged and hides behind cover again. You also cannot hit back if I enter close combat, strike you, disengage and move away. Monk attacks work by slowly chipping away HP from a far stronger enemy without taking damage. Per your rules this doesn't work because even if I attack first I will just get rekt by the inevitable counterattack. That is why I have the bonus actions and high movement speed to counter for my weak attacks and abysmal AC. Otherwise my survivability in combat is near-zero. I'm not a fighter or Barbarian who can tank damage.

So according to Vanilla, the troll can't shoot me if I pop up from the snow, shoot or strike him, dive back into the snow, burrow away or stay in place and hide as a bonus action (Stealth check). Because he doesn't know where I am in his turn. To do this, you have to make it clear he has readied an attack before it's my turn and he can't attack in his turn.

Regardless of cover, I'm under the snow and should count as Hidden because the enemy doesn't know I'm there or where I am.  Hidden means:  “Your opponent either doesn’t know that you are there, doesn’t pay any attention to you, or doesn’t know where exactly you are located” I should also have Surprise when I pop up the first time. So no trolls shooting me with fucking ballistas on sight.

And again Tamamo's right, such a hit and run strategy only saves you first time and from very dumb enemies. Then they can ready an attack and get you on your turn. But that must be stated beforehand. A hidden enemy also can't ready an attack. He has Surprise instead. I spent an hour looking into the rules and in's clearly stated that both players and the DM must make a Ready action clear beforehand and state what exactly triggers the action.

It's annoyingly complicated, I agree the Troll could anticipate or hear where I am burrowing and shoot me through the snow in his turn but there must be some heavy penalty because he can't see me and has to guess my location. I'd say that requires high WIS.
I don't really agree on the whole cover and stealth thing. The two things should be independent.
Hard cover is hard cover. Whether the enemy knows exactly where you are or not. I would also simplify shields in this regard.

Stealth and hiding provides cover where there are no physical barriers like the snow. You shoot from darkness, the enemy knows where you are. You have to move and re-hide or you lose the hidden condition. I've read that popping up and shooting an enemy should not give you advantage though, this applies if you sneak up an unexpecting enemy from behind. If the enemy sees you pop up, no advantage.

I have no idea how to reconcile all this with 'everything happens simultaneously' without completely redesigning the game. Realism is one thing but D&D isn't realistic. Under realistic conditions, 'heroes' no matter how strong would easily be overwhelmed by hordes of monsters.

I'm generally not happy with constantly learning what parts of your game completely differ from Vanilla. It makes planning ahead very hard. But we'll work it out. No need to rush things. Let's take a step back and clarify rules before we enter combat and things end in total confusion.

TL;DR
Every day we stray further from God Vanilla Rules

Cat listens to Ashley's report and at first all looks good. But then...

You all look in horror as the bald head of a giant beast emerges, followed by two very large arms and he pulls the ballista off the top of the wall, equipping it like a crossbow, he tries to aim it at Beatrice and you can just make out a shrill yell and he turns his head back toward his side of the wall. He then climbs down.

Cat is more fascinated than scared by the huge beast
Nyaa a Troll Nya? With a Ballista Nya? What's with this place Nya?


 

Yulya slaps her own cheeks with her palms to regain focus
For now we should stay hidden and prepare an ambush!
Cat you should go further South and hide then attack the beast from behind while it is busy chasing Alice. Ashley and me will stay here for ranged attacks and support.

Cat moves 30ft SW and hides behind the tree but stays within 30ft of Yulya within range of Emboldening Bond

I don't agree on this. D&D is a turn based game. You're not supposed to do anything on your enemy's turn except you have an abiliy like a reaction attack or if the enemy moves out of your striking range without disengage. The troll would have to withhold his action on his turn and state he will fire at Alice when she pops out in her turn. But otherwise classes like Monk have an extreme disadvantage to the point pf being unplayable. They live from hit and run and not being hit themselves because they're weak. Move from cover, strike, disengage, move out and hide behind cover. If I can just normally hit such an enemy on my turn what's the point? I could just stay out in the open. Alice is not a fighter who can tank damage. The rules are also explicitly made that she can't use a shield.

Picture the following. A goblin hides behind cover. Cat can't see him, doesn't even know where he is or even that he exists. Like we can't see the troll now.
On his turn the goblin runs out, fires an arrow at Cat and hides behind the corner again. Cat could not have fired at him on her previous turn because she did not even know about the goblin. What was she supposed to post? Only if she expects such an attack she can say 'I lay in wait and if an enemy shows up I fire at him.' This costs an action but must be stated beforehand. Otherwise there is a huge discrepancy between the DM and the players because you know the position of all characters and we do not.

Yes, such hit and run can be extremely annoying but it only works as surprise. At the 3rd attempt the enemy will lay in wait and snipe Alice if she always does the same. But at the first attach he'll be completely taken off-guard.