In Warner Bros. Entertainment's "LEGO Batman," players control LEGO versions of popular DC Comics heroes and villains from the Batman comics. Players start by controlling either Batman or Robin; once a section of the game is complete, players can replay the level as the villains (such as the Riddler, Clayface and the Joker). "A Poisonous Appointment" is the fourth chapter in the section called "The Riddler's Revenge." In this chapter, players control Batman and Robin and try to defeat Poison Ivy.
Travel right until you find bouncing parts for a bulldozer. Assemble the bulldozer and drive it over the large fountain in front of the greenhouse. This will allow you to build a suit-changer; build the suit-changer and have Batman jump in. He will change into the "Sonic-Suit Batman."
Use the Sonic Suit to break the windows of the greenhouse. Break the glass on the front door of the greenhouse to enter the next area.
Aim the Sonic Suit at glass lines feeding the plants inside the greenhouse. The plants block your way; destroying the glass tubes with the Sonic Suit kills the plants and clears your path. Walk through the greenhouse and destroy any glass you find with the Sonic Suit. A small alcove will open up. Switch to Robin.
Smash everything in the small alcove with Robin. A suit-builder will appear; build the suit-builder and have Robin jump in. He will change to the Attract Suit. Use the Attract Suit to collect the red, green and yellow debris pieces. When you collect 25, head right until you find the Attract Suit container (it will display the number "25" above it). Put the 25 pieces Robin collected into the container. A bomb will pop out and open the entrance to the caves.
Switch to Batman. Use a Batarang to break the blue object near a ladder; it will drop the ladder down. Cross the ladder and break the objects on the platform to reveal another suit-builder. Build the suit-builder and have Batman jump in. He will turn into the Heat Protection Suit.
Use Batman and go right. Jump on the glowing red bars and walk over the red-hot lava. You will notice pieces to build a tightrope; build the tightrope and cross it to enter the Laboratory. Switch to Robin.
Use Robin and destroy everything in the laboratory. You will notice little red, green, and yellow pieces. Use Robin's Attract Suit to suck them up. Place them into the container (again, you will need 25 pieces). Put 25 pieces into the Attract Suit Container and a door will open leading to the next area, the Toxic Pit.
Use Batman or Robin to destroy the lockers located on the back wall of the Toxic Pit. This will allow you to use the debris to build flowers. Build the flowers and you will be able to cross the toxic ooze in the center of the room. Cross the toxic ooze and destroy a switch to open the door. This will lead to the final area, the Hidden Garden.
Defeat Poison Ivy's Venus Flytraps by assembling the pieces located in front of them. Destroy three of them. Once the third flytrap is destroyed, you can attack Poison Ivy. Punch and kick Poison Ivy until her health bar reaches zero. A cutscene will show. The level will end.