The wizard Niak allows the goblins to enter with their payment of a diamond from the diamond mine.

How to Clear Gobliiins Level 4

Switch to Dwayne/Oups if you aren't already, then change the cursor to an open hand. Click on the floor nearby to put the diamond on the floor. Then click on the leftmost cup on the table on the left. Then switch the cursor to an arrow and click below the ladder to climb down. Then switch the cursor to a fist and click on the rightmost potted plant in front of the wizard's desk. The plant will eat the bee.

Switch to Hooter/Ignatius and change the cursor into a fist. Click on the face of the leftmost plant to make it grow. Then switch to Bobo/Asgard and change the cursor into an arrow, and click on the plant that grew, to make him climb onto the desk. Change the cursor into the fist, and click on the book on the right edge of the wizard's desk to knock it off.

Switch back to Dwayne/Oups and change the cursor to an open hand. Click on the diamond to pick it up. Then change the cursor to an arrow and click on the floor to the right of the plant that ate the bee earlier. Then click on desk above the book to climb up onto the desk. Change the cursor to an open hand and click on the wizard's hand to put the diamond into it. (If it doesn't work, try again.) After a cutscene, the level will be complete. Click the flashing "Go" in the hole that opened in the floor. Make a note of the code in the bottom-left of the screen ( FTWKFEN), then click anywhere to continue to the next level, The Giant Statue Room.