Looper killed that slime with no problem. He just completely absorb in that slime like it was nothing, but he realise that his level did not increase instead he heard a voice saying.

  "Slime has been caught. Do you want to name it?"

  "Wait What?!"exclaimed Looper

  "Slime has been named Waitwhat"said the voice in his head in a robotic tone.

  "No!I don't want to name him that!"Looper exclaimed frantically.

  However, the system did not reply him. He thought to himself:" No use crying over spilled milk." He then tried to summon the slime, the slime pop out right in front of him giving him a fright of his life. He command the slime to move to another spot and it did without any disobedience. Looper then thought about how his power works. He thought for a while trying to mimic the position of the thinker. He came to the conclusion that he is a monster tamer now.

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  He began capturing the other slime until his inner space is full. In total he caught about 25 slimes including Waitwhat. Then he experiment if that killing other monster  with the slimes will they gain experience or not. He climb up a tree and saw a sleeping lizard then jump from the tree landing on the lizard. When he landed on the lizard, he released all the slimes commanding them to attack the lizard.

  Since the lizard's body is covered in slime, he can't move hence he slowly get digested by the slimes. It was a long process that took about a few hours.