Interrupts, what are they?

[DxWings]

So I've been hearing about "interrupts during an opponent's casting time", exactly, how do you interrupt them, is it skill specific, such as putting an opponent to sleep before it can cast its spell? What moves are considered "interrupts"?

[Bixby]

Abilities that stun (Shield Bash, Brutal Swing, Leg Sweep, etc.) or silence (Blunt Arrow, Spirits Within, etc.), depending on the type of attack. Some moves can only be silenced. Some can only be stunned. Some can't be interrupted at all. There's no indication within the game to tell which is which. You just need to learn what you're supposed to stun/silence if it's your role to do so.

[Estellios]

Most of the time if something isn't immune to silence you can interrupt most magical- or voice-based moves.

As examples, the magic spells cast by Succubi and other demon enemies (Void Fire II, Void Thunder III, Mind Melt, etc) can be interrupted with a Silencing move.

Silence will also interrupt Siren's Lunatic Voice and Chimera's Ram's Voice and Dragon's Voice.

There is the odd one like ADS's High Voltage since it is a machine but those are rare.

Stun will interrupt anything with a cast time as long as the boss isn't immune to stun, at least what I have seen, but it also has a very long immunity time if you stun too much. Most bosses have an outright immunity to it as well.

[Sapphic]

Stuns and sleep have diminishing returns First time you use will give full duration, then proceeds to diminish in effect until the target becomes temp immune to the effect.

Silences, however, do not suffer that.

Seeing as youre listed as a Bard/archer. Your silence is Blunt arrow, which is a needed ability for Coil for example and pretty usefull in some other dungeons.

[ShadowDan]

Silences and Stuns are also usually not governed by the general skill cooldown, meaning they are always available for use unless on their own cooldown. They are meant to be used in a pinch to cancel out the big enemy attacks, those that have a casting bar.

[DxWings]

Alright! Thanks guys! I'm actually not at end game yet but would just like to know that before I get there.
So if I'm getting all the information correct, it's best not to spam these since the enemy builds immunity to it.
However, from using Blunt Arrow, it only seems to last one second, is that all its meant to do, is to just interrupt and not prevent an enemy from casting for a while?

[Mhaeric]

Its okay to spam them in fights that don't require stunning if the ability is off GCD, since you can weave them into your rotation for a dps increase. In fights where the interrupt is necessary you should save them for when needed. Examples would be DRG Leg Sweep and Spineshatter Dive.

[Estellios]

Alright! Thanks guys! I'm actually not at end game yet but would just like to know that before I get there.
So if I'm getting all the information correct, it's best not to spam these since the enemy builds immunity to it.
However, from using Blunt Arrow, it only seems to last one second, is that all its meant to do, is to just interrupt and not prevent an enemy from casting for a while?

You are correct. However, keep in mind that most of the spells/skills enemies use that have a charge time are the more devastating ones so don't discount it just because you prevent one move. Sometimes that move getting off means a wipe.

[Aykatu]

Something that has helped me was to move the Target Bar right over my character. I can see the hard cast bar pop up for the interrupt along with easily identifying mob's debuffs.