Is Expeditious Retreat essentially a spell to double your speed?

Question

I'm fairly new to DnD. I'm creating my first wizard and I've been wondering about the Expeditious Retreat spell.

The PHB says:

This spell allows you to move at an incredible pace. When you cast this spell, and then as a bonus action on each of your turns until the spell ends, you can take the Dash action.

Concerning the Dash action, the PHB says:

When you take the Dash action, you gain extra movement for the current turn. The increase equals your speed, after applying any modifiers.

My normal speed is 30 feet. So normally, during my turn in combat, I can move up to 30 feet and take one action (in any order, even splitting my movement up by moving 15 feet, taking an action, and moving another 15 feet, etc). Do I understand correctly that when I cast this spell and as long as it is active, I can essentially move up to 60 feet and take one action during my turn? That is, could the description of this spell be more simply (but equivalently) expressed as:

Your speed is doubled for the duration of this spell.

And if not, what would be the difference?

Answer 1

No, you can't simplify Expeditious Retreat that much. The difference is, Expeditious Retreat requires a bonus action to cast, and only gives you the ability to Dash as a bonus action.

So, in practical terms:

• You can't cast another spell on the same turn as you cast Expeditious Retreat, unless it's a cantrip.
• You can't both Dash as a bonus action and use another bonus action in a single turn.
• Your speed hasn't actually changed, so anything that involves your speed will still use your real speed.
• For example, if you Dash as an action and Dash again as a bonus action, you can move 90 feet in a turn, whereas if your speed was doubled, and you Dashed as an action, you would be able to move 120 feet in a turn.

There's a lot more differences between Expeditious Retreat and the simplified version you propose, but I tried to restrict myself to ones that are relevant to you.

Answer 2

The spell says it lets you Dash as a bonus action.

Your movement allows 30 total feet of movement.

Then you have your Action that lets you attack, move again, etc. … or Dash to add 30 ft.

Then your bonus action can be a Dash action, which is an additional 30 ft.

90 ft. total movement.

Answer 3

Have to disagree with it giving you 90 foot movement. It doesn't give you extra speed, it only lets you use the Dash action, as a bonus action. You're still using dash, which is a specific action that doubles your base movement. Dash is NOT +30 speed, it's x2 base movement speed. You're not using magic to increase your speed, you're using magic to change when you can use a pre-existing action, with a non-magical effect.

When you use Dash as a bonus action, it allows you to move 60 feet, then attack, or move 30 feet, attack, then Dash and move another 30 feet. One thing it does NOT allow you to do, is move 30 feet, attack, dash, move another 30 feet, then use your extra attack. When you have Extra Attack, it lets you do a 2nd attack as part of your Attack action. When you use a bonus action, it means you have finished using your action.

So to repeat:

• Dash is not a magical action, it is a physical action, to double your base movement speed.
• This spell only allows you to use it as a bonus action, instead of an action, allowing you to attack before, or after, using dash.
• When you have extra attack, you can not start an attack action, then bonus action dash, then use your extra attack. You can however, use your bonus action first, move 30 feet to one enemy, use your attack action to attack the first enemy, then move another 30 feet and use your extra attack on the 2nd enemy. You basically just can't use a bonus action in the middle of an attack action. You have to finish it, before using the bonus action.

• Whatever your current base movement speed is, dash doubles it. Some effects double your movement speed, some half it, some add speed, some reduce speed. So if you have a spell active, a magical item, or use a special ability, like Tabaxi's Agility, your base movement speed is first increased by that, then the new base movement speed is doubled by dash. (For example: First turn, you bonus action activate your boots of speed, your BASE speed is now doubled, and your new speed is 60 feet. Then, your 2nd turn, you bonus action activate zephyr strike, a concentration spell that gives you +30 BASE speed when you hit an enemy. Then, your 3rd turn, you hit someone, meaning your pre-boots base speed is now 60 for 1 turn, meaning the boots double it to 120. Then, now that zephyr strike has taken effect, you can use the new concentration spell, expeditious retreat, that allows you to bonus action Dash, including on the turn you cast it. Dashing while your base speed has +30, and is then doubled to 120, means you can dash 240 feet on that turn. The next turn however, the +30 of zephyr strike runs out, and your base movement speed returns to 30, doubled by the boots, into 60, with a dash movement speed of 120)

• Expeditious retreat is a concentration spell, meaning it only allows you to Dash as a bonus action, while you're concentrating. If you use any other concentration spells (like zephyr strike) after using expeditious retreat, you lose the ability to bonus action dash. You can, however, take advantage of expeditious retreat, to bonus action Dash, then drop the concentration spell, to use a new concentration spell on the same turn, but only if it has a casting time of 1 action, not 1 bonus action