The moment Kretos decided that he would win the tournament, he looked for Afeus to ask him to help him gather information. Afeus was at first reluctant to stop his research but when Kretos told him that he was willing to share his insights regarding magic, Afeus changed his tune real fast.
The two of them proceeded to go around the school asking the students that were at the previous tournament about the opponents they faced.
...
While Kretos was going around gathering information, at the Grand Mage's mage tower, three demons have gathered. One of these demons present was the maid that killed Lisa and Matias. Another who had just arrived looked like the deceased Grand Mage, but once he entered the room his face turned into that of a young man.