Reaction spells

Quote from The_Murgen >>

ANOTHER QUESTION on reactions:
Can you voluntarily upcast a Reaction spell, like Hellish Rebuke.  I know Warlock has to cast it using their available pact slots, but what about other caster?

Say, my bard acquires Hellish Rebuke with Magical secrets.  If they had a higher level spell slot available, could they choose to upcast it during the reaction?

If you cast a spell by expending a spell slot then you are able to up-cast it regardless of what type of action you use to cast it.

Yes, casting a spell as a reaction (or bonus action) still follows all the same rules for upcasting as casting as an action

Quote from Random60275 >>

in the new edition, i can't cast a spell as a reaction (shield, counterspell etc) if in my round i cast a spell that required a slot. right?

so if I think I need the shield or counterspell spell, should I think about it first and only use cantrips or spells that don't require slots?

 

So the issue is you said "if in my round", but the rules say "in any given turn"

Turns are basically counted off as individual initiative numbers, whoever rolled an 18 for initiative, when the dm calls off that players time to go, thats their TURN.

A ROUND is all the initiave rolls, from highest to lowest, for one go. When the person with the lowest initiative finishes their turn, thats also the end of the ROUND. and the next round starts at the top of the initiative.

So if you burn a slot on your turn to cast firebal, and then later the bbeg does a bite attack against you on their turn, those are different turns, so you can burn another slot if you have a reaction, to cast shield

Quote from SunIsGettingRealLow96589 >>

Quote from Random60275 >>

in the new edition, i can't cast a spell as a reaction (shield, counterspell etc) if in my round i cast a spell that required a slot. right?

so if I think I need the shield or counterspell spell, should I think about it first and only use cantrips or spells that don't require slots?

So the issue is you said "if in my round", but the rules say "in any given turn"

Turns are basically counted off as individual initiative numbers, whoever rolled an 18 for initiative, when the dm calls off that players time to go, thats their TURN.

A ROUND is all the initiave rolls, from highest to lowest, for one go. When the person with the lowest initiative finishes their turn, thats also the end of the ROUND. and the next round starts at the top of the initiative.

So if you burn a slot on your turn to cast firebal, and then later the bbeg does a bite attack against you on their turn, those are different turns, so you can burn another slot if you have a reaction, to cast shield

Mostly spot on.

There is the edge case to consider where you expect an attack or spell on your turn. If you anticipate an Attack of Opportunity, a Readied Action, or any other Reaction that involves an Attack Roll or Spell, you may wish to hold off on using a spell slot until after the potential trigger has passed in case you need to respond with your own Reaction to cast Shield or Counterspell.

Apart from that one, rare scenario, I agree with you.

Quote from Random60275 >>

in the new edition, i can't cast a spell as a reaction (shield, counterspell etc) if in my round i cast a spell that required a slot. right?

so if I think I need the shield or counterspell spell, should I think about it first and only use cantrips or spells that don't require slots?

 

 you can still cast your spell. reaction would be triggered on a different turn .

But the thing is, Reactions can also trigger on your own turn:

Certain special abilities, spells, and situations allow you to take a special action called a Reaction. A Reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else’s. The Opportunity Attack, described later in this chapter, is the most common type of Reaction.

A Reaction is a special action taken in response to a trigger defined in the Reaction’s description. You can take a Reaction on another creature’s turn, and if you take it on your turn, you can do so even if you also take an action, a Bonus Action, or both. Once you take a Reaction, you can’t take another one until the start of your next turn. The Opportunity Attack is a Reaction available to all creatures. See also “Opportunity Attacks” and chapter 1 (“Actions”).

And the two spells mentioned by Random60275 can indeed happen on your own turn: Shield (e.g. if you provoke an Opportunity Attack from another creature), and for Counterspell, we have this SAC answer as an example:

Can you cast a Reaction spell on your turn?

Yes, but you must abide by the rule of expending only one spell slot to cast a spell on your turn. For example, if you take a Magic action to cast Fireball using a spell slot and an enemy casts Counterspell, you can’t also then expend a spell slot to cast Counterspell targeting that enemy.