Hmmm seems as if I brought up a tricky question. I agree that I thought extra and multi attacks would be one action but some disagree so I'm not sure which way to go on it.
https://twitter.com/JeremyECrawford/status/557812617369378816
The guy answering this is generally taken as Wizard's mouthpiece.
Yeah, I think the RAW + Crawford makes the official intent pretty clear.The "on it's turn" language clarifies things for me.
I agree that by the RAW and seemingly RAI as well, you won't get more than one attack as a reaction by using Ready if you have the Extra Attack feature. "Specific trumps general", Extra Attack is more specific than Ready, and unfortunately it mentions that it works only on your turn.
I don't know if this is fair or not. Cast a spell is an action than can be used as a reaction via Ready, but then there is an added cost (the need for concentration between Ready and Cast). So one hand, you can use the full 'power' of spellcasting with Ready, but with a complication, so I am not sure if you should be allowed to use the full 'power' of multiple attacks.
But I don't think it would break the game to allow it, you are just doing the same amount of attacks that you could do in a round, just trying to get some advantage by waiting, but you always risk losing them all if the trigger doesn't occur.
Yeah, warlocks get the best cantrip ready overall, but have to give up that Hex that could have lasted all day otherwise.So it feels like things are a little trickier for everybody when it comes to readied attacks, and that is clearly the design goal.
Players can only do it on their turn because the Extra Attack feature says "on your turn". Monsters don't get the same wording. Although I don't see any harm in limiting them similarly if you want.
Dungeon Master's Basic Rules said:MULTIATTACK
A creature that can make multiple attacks on its turn has the Multiattack ability. A creature can’t use Multiattack when making an opportunity attack, which must be a single melee attack.