Spells like Moonbeam, Flaming Sphere, and Call Lightning allows you to use either an Action or a Bonus Action (depending on the spell) to trigger a specific effect on subsequent turns. Does triggering these effects count as casting a spell?

I'm fairly sure that one can't Counterspell them once it has been casted, but would it trigger the Mage Slayer feat, for example? (Assuming all conditions for Mage Slayer are met)


2 Answers 2


Casting a spell uses the 'Cast a Spell' action.

From the section 'Actions in Combat':

When you take your action on your turn, you can take one of the actions presented here, an action you gained from your class or a special feature, or an action that you improvise. [...]

Cast a Spell
Spellcasters such as wizards and clerics, as well as many monsters, have access to spells and can use them to great effect in combat. Each spell has a casting time, which specifies whether the caster must use an action, a reaction, minutes, or even hours to cast the spell. Casting a spell is, therefore, not necessarily an action. Most spells do have a casting time of 1 action, so a spellcaster often uses his or her action in combat to cast such a spell.

You are casting a spell only when you take the Cast a Spell action. The actions described in those particular spell descriptions are not the Cast a Spell action, rather they are "an action you gained form a special feature".

Counterspell does not work here.

Counterspell's trigger says:

which you take when you see a creature within 60 feet of you casting a spell.

Since the actions mentioned in these spell descriptions are not "casting a spell", counterspell cannot be used.

Mage Slayer does not work here.

Similar reasoning as counterspell. The first point of Mage Slayer says:

When a creature within 5 feet of you casts a spell


Not viable for counterspell or anything else that triggers off of 'casting a spell'

As you've stated, those continuing actions/bonus actions on an active spell are just that - continuing actions. You aren't casting a new spell and/or using components. You are just using a function of the spell.

which you take when you see a creature within 60 feet of you casting a spell

Counterspell is only a viable reaction if a creature is casting a spell. Without that specific action, there is nothing to counterspell. That spell is really just about attempting to stop someone from completing a casting.

If you want to stop a currently active spell, your best bet is dispel magic or something similar that works against currently active spells or magical effects.


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