Dubior is a mid-boss appearing only in Kirby's Return to Dream Land. Oddly enough, it gives the Spark ability when inhaled, likely because the UFO ability isn't in the game.
Physical Appearance
It is a UFO-like robot that has two yellow eyes and an antenna that has three strips of metal that change from yellow to red. Its head is colored in a shade of metallic yellow and the underside of it is a coppery orange. Surrounding Dubior are 5 stubs floating of metal that are detached from it. The tips are orange and the tops near its head are yellow.
The EX counterpart is pink in color and has only one eye. The underside of its head is now dark blue and the tips of the revolving metal around it are pink as well. Dubior EX has more health and its attacks deal more damage than the original's.
Dubior EX
Attacks
Dubior's attacks include a charged ram that deals lots of damage, a lightning-bolt attack from above that strikes repeatedly, and the ability to spawn two (four in extra mode) Dubior Juniors (miniature versions of itself), which will then zigzag around and may be inhaled to obtain Spark.
A great opportunity to strike is right after the charged ram, due to the fact that it will sit there stunned for several moments. Dubior is usually fought before a puzzle that requires the Spark ability to complete.