The climax provided in Act 3 occurs when Bottom’s head is replaced with that of an ass, and the anointed lovers gather together, argue, and fall asleep.
A Midsummer Night’s Dream is broken up into two subplots that have a scene in Act 3. In most Shakespeare plays, Act 3 serves up the climax, in its place in the traditional plot diagram, with Act 1 providing the exposition, Act 2 the rising action, Act 4 the falling action, and Act 5 the resolution. Remember that the climax is the turning point in a play, where the characters cannot return to where they were before. It is also the most exciting or interesting part.
Act 3, Scene 1
In the first subplot, we have the craftsmen. They are rehearsing their play within a play in the woods. Bottom wanders off, and when he returns his head has been replaced with that of an ass!
Why do they run away? This is a knavery of them(105)
to make me afeard.
O Bottom, thou art changed! What do I see on
thee? (Act 3, Scene 1)
Puck is having some fun with him, because the “rude mechanicals” are getting too close to Titania, Queen of the Fairies. The other craftsmen are frightened and run off screaming. Bottom is sad, and has no idea why. He remains in the woods. This is important, because now he is in the world of the fairies, and will remain with Titania.
The significance of this scene as a climax is that Bottom is not among the actors anymore, and they think their play is lost. It’s a turning point for him personally, because he is about to go on a wild ride.
Act 3, Scene 2
One of the keys to this play is that the wrong people seem to have fallen in love. Puck, the mischievous magical being, is in the forest in Act 3 with Hermia, Helena, Lysander, and Demetrius. He is trying to anoint the lovers’ eyes to make them fall in love.
Hermia is supposed to marry Demetrius, but it is actually Helena who likes Demetrius. Helena likes Lysander. Puck was supposed to anoint Demetrius’s eye, and instead he put the love potion on Lysander, thus causing Lysander to fall in love with Helena, instead of Demetrius. This confuses Helena to no end, and she assumes that he is making fun of her, since he is supposed to be deeply in love with Hermia.
You do advance your cunning more and more.
When truth kills truth, O devilish-holy fray!(130)
These vows are Hermia's. Will you give her o'er? (Act 3, Scene 2)
When Demetrius wakes up and also tries to profess his love for Helena, she thinks he is teasing her too and gets really distraught. When Hermia comes in and also tries to talk to her, it does no good. She’s convinced they are all out to get her and it’s a vast conspiracy. You can kind of see her point. The two guys are professing that they are madly in love with her, acting very strangely, and Hermia keeps asking what’s wrong, unable to figure out why Lysander is interested in Helena now.
Naturally, Helena and Hermia begin to argue.
O me! you juggler! you cankerb lossom!
You thief of love! What! Have you come by night,
And stolen my love's heart from him? (Act 3, Scene 2)
In the end, everyone gets tired! Demetrius and Lysander decide the only way to settle this is the manly way, with a duel. They run off to fight and eventually fall asleep (that was Puck’s plan). Hermia chases Helena until they fall asleep. Once they are all asleep, Puck breathes a sigh of relief, glad that he can anoint again so that they fall in love with the right people this time. If at first you don’t succeed, anoint, anoint, again!
This is the turning point because the lovers were at an impasse. Fortunately, Puck’s interference is at an end. Their strange behavior, and their own personalities, both contributed to the conflict. When the wrong lovers were paired (or en-triangled), chaos ensued. It might also have been a lesson to Puck to get his facts straight before he went around anointing people with his love juice. Still, he enjoyed the chaos that ensued while it lasted, and at the high point at the end of Act 3 things were about as wild and crazy as they could get before, in grand Shakespearean fashion, everyone fell asleep!
Some would say that A Midsummer Night's Dream doesn't have a "true" climax, as every problem that all the characters have been dealing with throughout the entire play are resolved in Act IV by magic. It's hard to call that a climax because using magic does wrap things up, but doesn't create a natural climax in the traditional sense as there is no tension.
Thus, the climax of the entire play takes place in Act II, Scene 2. Lysander and Demetrius are both after the love of Helena. Both Hermia and Helena are amazed by the intensity of the battle for Helena's heart. The two men go look for a place to fight, while Hermia challenges Helena to a fight too.
The physical manifestation of the lovers' love triangles and quadrangles doesn't resolve the issues, but does bring them to a head. Just after this, all four run off and Puck and Oberon use trickery to get them into the right romantic alignments. This sequence could be considered the climax of the Act and of the entire play.