If you forgot how to make monsters come to your side(convert), then read the
following: First, purify the monster chosen by you to be a part of your team.
Second, keep purifying the monster until the box at the top when puryifing
says, "Will convert no matter what". Then kill the monster and after you kill it a
box will appear saying such and such monster has joined you. If you have already
converted one type of monster and want to convert a different monster of the
same kind, you will not have to purify it until the point where it says "Will convert
no matter what". Make sure you consistently train you monster or it will dislike you
and run away.