Maniacal Laugh can easily turn the tide of the battle, or even potentially end the game. Using this on an already strong zombie will most likely obliterate plant defenses. And due to its nature of giving the Frenzy trait, if the zombie manages to destroy a plant, which it will most likely do due to its huge stat boost, it will attack again. Frenzy zombies like Smashing Gargantuar and Vimpire are best left alone from this trick, as other zombies may be more favorable to give the Frenzy trait too.
This trick is very good for almost any zombie, but it's better used when a powerful zombie is on the field, because it's quite expensive to use. Use this on Undying Pharaoh, because the Undying Pharaoh won't let the zombie hero's health go less than 1 and it will give him the Frenzy trait, so it can go through plants and also hurt the plant hero. Try using this trick with Paparazzi Zombie, because it will give him +6/+ 6 and the Frenzy trait, because it's a trick. Using this on a zombie with Strikethrough, such as Hot Dog Imp, can guarantee heavy damage to the plant hero.
If you are Immorticia and have this card along with Shieldcrusher Viking use it on said zombie, as he will have +5, the Bullseyetrait, and the ability to drain the enemy's Super-Block Meter, making for a very powerful threat, and essentially ending the game in two turns (if not defeated or a Soul Patch is used). Additionally, Maniacal Laugh is also useful on Nurse Gargantuar as he may constantly attack a plant and the plant hero, all in total of 9 damage to the plant and 9 damage to the plant hero; 18 health healed which can really turn the tide of the whole battle. Electric Boogaloo can use this on many Crazy cards such as Template:PvZHLink, Jester, and Exploding Imp, making them huge threats. Using this in a pet zombie deck, such as with Cat Lady, can massively help. Maniacal Laugh on Template:PvZHLink or Template:PvZHLink can also essentially end a match. The Smash has access to Hearty zombies, which can become really tanky and powerful. However, The Smash also has access to Coffee Zombie, which can give many zombies Frenzy at once, so these cards are interchangeable.
Against
When this is used, it is best to Bounce the zombie as soon as possible as it will remove its stat boost and Frenzy. Using something like Template:PvZHLink to destroy the zombie instantly also works well. However, this can only happen if the player survives the Fight phase since zombie tricks happen after plants get to play.
Wall-Knight can use Uncrackable to avoid taking damage, allowing the player to stall and avoid taking damage, although you will not be able to react to this move on the turn it's used. Using tricks or fighters that allow you to Freeze zombies, such as Template:PvZHLink or Template:PvZHLink can also stall a zombie buffed from Maniacal Laugh for a turn or more. Ideally, Root Wall or Template:PvZH Link can also be used if a plant is in the same lane as the buffed zombie.
A counter to a zombie buffed through Maniacal Laugh is using a plant with the Bounce effect, such as Template:PvZHLink. Bouncing simply reverts that zombie to their original stats and removes the Frenzy trait from them.
Gallery
Maniacal Laugh's statistics
Maniacal Laugh's card
Maniacal Laugh in an advertisement for the Royal Court Pack
Beastly class. It costs 6
to play, and its ability gives a selected zombie +5
/+5
and the 
Frenzy trait.
/+5
Strikethrough, such as Hot Dog Imp, can guarantee heavy damage to the plant hero.
Bullseye trait, and the ability to drain the enemy's Super-Block Meter, making for a very powerful threat, and essentially ending the game in two turns (if not defeated or a Soul Patch is used). Additionally, Maniacal Laugh is also useful on Nurse Gargantuar as he may constantly attack a plant and the plant hero, all in total of 9 damage to the plant and 9 damage to the plant hero; 18 health healed which can really turn the tide of the whole battle. Electric Boogaloo can use this on many 
Crazy cards such as Template:PvZHLink, Jester, and Exploding Imp, making them huge threats. Using this in a pet zombie deck, such as with Cat Lady, can massively help. Maniacal Laugh on Template:PvZHLink or Template:PvZHLink can also essentially end a match. The Smash has access to 
Hearty zombies, which can become really tanky and powerful. However, The Smash also has access to Coffee Zombie, which can give many zombies 
Freeze zombies, such as Template:PvZHLink or Template:PvZHLink can also stall a zombie buffed from Maniacal Laugh for a turn or more. Ideally, Root Wall or Template:PvZH Link can also be used if a plant is in the same lane as the buffed zombie.
Brainy
Crazy
Hearty
Sneaky