As a refresher, and because I've seen it done other ways elsewhere, I'm going to lay out the actions in combat.

In combat, you can:

• move up to your speed, and
• take an action, being a choice of:
  
  • attack,
  • cast a spell,
  • dash,
  • disengage,
  • dodge,
  • help,
  • hide,
  • ready,
  • search,
  • use an object,
• take a Bonus Action, if you have any
• make a reaction, if you can

Chop and change the order however you like, but it's still 1 movement, 1 action, possibly 1 bonus action, and maybe 1 reaction.

Using this, if I were to dash during my turn, I would not then be able to attack as well (unless I had a feat or trait (like the Fighter's Action Surge) that allowed me to make an attack as a Bonus Action).

Note also that at higher levels, you may have more than one attack available to you.  This means that when you take the attack action, you make make two attack rolls.  It is not the same as taking two actions; you could not attack with your longsword, and cast a spell, as those would be two actions.

Posting in Combat

Play by post games are a little different to playing face-to-face or over a streaming service.  Because we're all in different locations and on different time zones (I'm on the Australian East Coast, for instance), and we have so many outside interferences, it does not make sense to rely on the initiative order for posting.

When Combat starts, I will roll initiative for everyone.  Post your actions however you like (keeping in mind the 1-1-1-1 rule above).  Once I have all of the actions in (or enough time has lapsed -- typically 48 hours or so), I will post the results of the combat round, in initiative order.  This will help keep the game moving, even if someone can't get to the keyboard in time.

You do not have to post in initiative order.

You can only post once during a combat round.

When posting, please Roleplay your actions, and do not include any Out of Character (OOC) information.

After your In-Character (IC) post, insert a <HR> below your last line, and then include your out of character information:

• Where you are moving too (the grid number if there's a map)
• your action and your target (by name or number)
• any rolls which apply (copy/paste from the dice roller)  For ease of posting, roll both your attack roll and your damage roll.  If the attack is unsuccessful, I'll ignore the damage roll, but it's faster than needing to go back-and-forth several times to roll to hit and then roll damage.

Once everyone (or a majority) has posted (and I've given sufficient time to allow stragglers to post), the I will resolve that round.

Example:

So the question's come up twice, which means it needs a group answer.  Fair enough.

Attacks of Opportunity

1.  I'm going to assume you take an attack of opportunity whenever the *ahem* opportunity presents itself.  I will roll the dice for you to speed things up if that happens.

2.  In most cases, you're going to only get an attack of opportunity on one target.  However, there are crazy times when you might have more than one target in range who decides to move away in the same round.  My default assumption is this: you're going to attack the first creature that presents the opportunity (i.e.: the one highest in the initiative order, since they'd be running away first), and ignore the second (since you only have 1 reaction to use).

3.  If you have used your reaction for something else (casting a spell, grabbing onto a teammate who's about to fall off a cliff, etc.) then you don't get an attack of opportunity.

4.  If you have a feat (like War Caster, that allows you to make a non-melee attack, I'll be asking you what your default reaction might be.

All other cases will be decided on an as-it-comes basis.

We are using a modified version of Lingering Injuries.

I'm going to keep the exact effects behind the DM's Screen for now, but suffice to say that it's harder to get longer-lasting detrimental effects.

However, you should know the rules which trigger these Lingering Injuries.

1. When reduced to zero hit points and not killed out right you need to make a Death Saving Throw (DC 10) at the beginning of each of your turns.  This is the standard rules-as-written on DnD 5e.
   
2. If
   
   • you are stabilised by another player,
   • succeed in all saving throws,
   • are lucky enough to roll a natural 20, or
   • are healed before your turn
   
   You do not suffer any lingering injuries.
   
   
3. The number of any FAILED Death Saving throws you make before being stabilised or revived indicates triggers a Lingering Injury.  One failed death save will typically trigger a minor injury, while two failed death saves will trigger the major version of the same injury.  Three failed death saves results in death, always.

I'm going to scrap this house rule.  The more I think about, the more it seems unnecessarily number-crunching -- and sometimes in ways that don't make sense, given the circumstances of battle.

Plus, it hasn't come up at all.  So there's that.

After reading a few threads on DnD Beyond, I'm now leaning more towards exhaustion as applied whenever a character drops to 0 hp and is revived.  It's less number-crunchy, utilises an potentially underused game mechanic, and still discourages the whole whack-a-mole strategy of combat.

Thoughts?  Concerns?  Happy to discuss here, or on discord.