Get the most out of your pact of the chain familiar

I've been experimenting with my imp familiar. It's extremely useful - to the surprise of no one I'm guessing. But still there were some things I just hadn't pieced together - most importantly regarding the "When you take the Attack action, you can forgo one of your own attacks to allow your familiar to make one attack with its Reaction." part of the pact of the chain.

It was always awkward to use the attack action to give my familiar the reaction to attack a foe because it might not be positioned correctly - seeing as it's usually invisible and foes use their movement to go someplace else to attack my friends. So unless my enemies are already locked in combat the imp was usually not within reach of anyone. So the solution is to ready the attack action to when the imp is in melee range of an enemy. 

Doing this, once it's my familiars turn they move next to an enemy which triggers my ready action for them to attack - with advantage because they are invisible. Then the imp uses it's action to turn itself invisible, and spending any extra movement to reposition out of reach (fly up a bit).

But here is a question. Say I have investment of the chain master and flock of familiars. Would that mean that on my turn I could use my bonus action to make one of my imps do a reaction attack (this is not as handy as the attack on the imps turn because it's then revealed to the battlefield until it's turn) AND ready an action to give one of my other flock familiars a reaction attack when it's their turn like normal? 

I've found this to be extremely influential for both combat and exploration on lower levels. An invisible imp in spider or raven form is a very good scout. Anyway, just wanted to share what I've learned about using pact of the chain recently. It's been a lot of fun.

You can not use this feature to have your familiar Ready the attack. They have to actually make the attack right when you use the feature. 

The process looks like this if you only have one attack (no extra attack or Thirsting/Devouring Blade): Your turn starts and you take the Attack action. Instead of attacking the enemy yourself, you forgo the attack to command your familiar to make an attack. The familiar immediately uses its reaction to make an attack.

The familiar does not have the option to move before making the attack that you triggered by forgoing one of your attacks - it happens immediately.

The familiar isn't readying the attack. You are. The familiar acts on it's turn by moving towards an enemy triggering your reaction to make the attack action. You then use your attack action to grant your familiar a reaction to make an attack.

• You can ready an attack action with the criteria "when my familiar is within melee range of an/this enemy"
• When you take the Attack action, you can forgo one of your own attacks to allow your familiar to make one attack with its Reaction.
• => the familiar moves into melee range, triggering your reaction to use the attack action. You then forgo your attack (of course you don't get extra attacks) to grant your familiar an attack. 
• Familiar uses it's reaction to attack
• Familiar continues it's turn. Using it's own action to turn invisible
• Familiar continues it's move, if it has any left.

What rule forbids this?

Ok, I see where you are going with this. That actually can work, but it would eat up both your own and your familiar's reactions. In most cases, it would probably be more advantageous to just attack on your own since familiar attacks tend to be less effective than your own attack with a weapon/cantrip. The only time I can think of this would be worth your whole action to have your familiar attack is if you really wanted to trigger a rider effect, like with the Quasit's Rend attack that causes the Poisoned condition.

Yeah, this is for pact of the chain familiars. Imp does 1d6+3 (+2d6 poison) on a +5 advantage (because of invisibility) attack. 3d6+3 is nothing to sneeze at during early levels. 

Once you get to lvl5 and get investment of the chain master you can do this (with a bonus action now which competes with other bonus action concentration spells) and attack. But you lose the ready reaction maneuver. Meaning the imp will be visible after it's reaction attack until it is it's turn. Making it more vulnerable. 

The issue is, if you ready an attack, you are not taking the attack action. You are taking the ready action, then later using your reaction to make an attack.

Since the power works “when you take the attack action” as opposed to when you make an attack it would not trigger, since you took a different action.

It’s similar to how a fighter level 5+ who gets multiple attacks and readies an attack only gets one attack. They are not taking the attack action, so their extra attacks don’t happen. 

Quote from Xalthu >>

The issue is, if you ready an attack, you are not taking the attack action. You are taking the ready action, then later using your reaction to make an attack.

Since the power works “when you take the attack action” as opposed to when you make an attack it would not trigger, since you took a different action.

It’s similar to how a fighter level 5+ who gets multiple attacks and readies an attack only gets one attack. They are not taking the attack action, so their extra attacks don’t happen. 

The description of the Ready action does say that you "choose the action you will take in response to that trigger", so it certainly seems like you are actually taking that action. 

The reason Extra Attack usually doesn't work with a readied action is that Extra Attack specifically says it only applies "whenever you take the Attack action on your turn" and in most cases the readied action is happening on someone else's turn.