Your Action Economy, Explained
Combat in D&D 5e is deceptively simple on the surface and genuinely overwhelming the moment you start pulling at the threads. Actions are where most of that complexity lives, and most players only ever use two of them.
The Ones Everyone Knows
Attack and Cast a Spell will cover the majority of your turns at any table. Both are getting their own deep treatment in future episodes, but the short version is this: if you want to deal damage, you are almost certainly doing one of these two things. The rest of the action list exists for the turns when a straight attack would be the wrong call.
Dash doubles your movement for the turn. Disengage lets you leave melee range without eating an opportunity attack. Dodge is the sleeper pick that almost nobody uses, and it is genuinely good. When you take the Dodge action, all attacks against you have disadvantage until your next turn, and you get advantage on Dexterity saving throws. When a dragon is about to breathe fire and you have nothing better to do, Dodge is not wasted turn. It is the correct turn.
Help is where things get interesting and contested. In combat, you are distracting an enemy so an ally has advantage on their next attack roll against that target. Fine, clear, useful. Out of combat, it becomes the most spammable and most abused mechanic at any table. The rules are permissive enough that players will try to Help on basically everything, and the right answer as a DM is to make them justify it. Pulling a rope with five people? Yes, Help. Watching someone pick a lock and whispering encouragement? No.
The Ones the Dungeon Master’s Guide Is Hiding From You
The optional action rules in the Dungeon Master’s Guide are where combat stops being a resource management game and starts feeling like a fight. Climbing onto a Bigger Creature is exactly what it sounds like. If a creature is at least two size categories larger than you, you can use your action to make an Athletics or Acrobatics check contested by the target’s Acrobatics. Win, and you move into its space. The creature treats this as difficult terrain for you, and where you end up on the creature matters for whether you get advantage on attack rolls. This is not a gimmick. It is Shadow of the Colossus as a rule set.
Disarm uses your attack roll contested by the target’s Athletics or Acrobatics check. No damage, but the item hits the floor. The attacker has disadvantage if the target is holding the item with two or more hands. The target has advantage if it is larger than the attacker, and disadvantage if it is smaller.
Mark is the odd one. When you make a melee attack against a creature, you can mark it. On your next turn, if that creature provokes an opportunity attack from you, you get advantage on that attack and it does not expend your reaction. That last part is the important bit. Your reaction is still available for other things.
Overrun, Shove Aside, and Tumble are all variations on moving through or past a creature. Overrun and Tumble are essentially the same action, just Athletics versus Athletics for one and Acrobatics versus Acrobatics for the other. Shove Aside moves a creature 5 feet laterally rather than back, which matters precisely when you need to put someone next to something dangerous.
The Rule That Covers Everything Else
Improvising an action is technically in the rules, and it is the most important one on the list. If a player wants to do something that has no written mechanic, figure out what ability check makes sense, set a DC that reflects how plausible the thing actually is, and let them try. Ask what they want to do, how they are doing it, and why. The why tends to reveal whether the idea is creative or just chaos. Either way, it deserves at least a second of genuine consideration before you say no.