After the goblins give Niak the diamond, the wizard opens a passage in the floor, to a room with a giant statue.
How to Clear Gobliiins Level 5
Switch to 
Hooter/Ignatius, then change the cursor to a fist.
Click on the short piece of grass at the base of one of the giant statue's
hands. The grass will grow tall.
Switch to 
Bobo/Asgard, change the cursor into an arrow,
and click on the tall piece of grass to make
him climb up it. Then change the cursor to a fist and click on the statue's
eye to punch it, making its tongue come out.
Switch to 
Dwayne/Oups and have him stand on the tip of the tongue,
but leave room next to him so another goblin can stand next to him later.
Then switch to Hooter/Ignatius and change the cursor to a fist.
Click on the metallic object that is sticking up out of the casket in the
upper-left part of the screen. Then
quickly change the cursor to an arrow and click the tip of the tongue
to make Hooter/Ignatius stand next to Dwayne/Oups on
the tongue. A skeleton will come out of the casket, so you have to be quick
to get Hooter/Ignatius out of the way so the skeleton
won't scare him.
As soon as Hooter/Ignatius and Dwayne/Oups are both
standing on the statue's tongue,
switch to Bobo/Asgard and change the cursor to a fist, and
punch the eye. The tongue will lift Hooter/Ignatius and
Dwayne/Oups up, so nobody is in the path of the skeleton. The
skeleton will scare away the ogre, revealing Airain's Mushroom. Wait for the
skeleton to go past the statue's tongue, and have Bobo/Asgard
punch the statue's eye again. Switch to Dwayne/Oups and
change the cursor to an open hand, and click on Airain's Mushroom.
Wait for the skeleton to go back into its casket if it isn't there already. This completes the level. Click the flashing "Go" where the mushroom was. Make a note of the code in the bottom-left of the screen ( ), then click anywhere to continue to the next level, The Spider Cave.