Platinum King Jewel

The Platinum King Jewel is the epitome of the Metal Slimes in Dragon Quest as despite only appearing in 4 main series games it has the highest HP, attack, defense, agility, and EXP of the Metal Slime family and it can even dazzle your party which makes them miss their attacks so much that doing any damage is virtually impossible if it decides to use it making it even more difficult to defeat then even a Metal King Slime if it decides to stick around.

Example of:
Metal Slime