First of all you need to get Maguen Plasma Collector from Nemo, he has a second option to practice.
When you kill Elite Monsters in Seed of Annihilation there is a 5% probability to appear a Wild Maguen to one member of the party. The Maguen will display one of three different particle effects above its head. The chance to get a Maguen with one color or another is 1/3, completely random.
You have 10s to use your Maguen Plasma Collector, if you are fast and succeed it will cast one buff depending on his color effect, Bistakon, Cokrakon or Reptilikon. The three buffs are stackable. The level of the effect can raise if a Maguen casts a buff that you already have, up to level 3.
If you have 1 buff to level 3 and one maguen with the same color casts a buff on you, you have a 70% chance to get a buff which increase your stats at level 1 and 30% at level 2 (Power, Speed and Critical). These buffs are not stackable and you can get a level 1 buff while you have some at level 2.
If you have all buffs at level 1 or one at level 3 you have a 0.095% chance to get a Maguen Collection Box and0.0045% to get a Elite Maguen Collection Box. So almost 0.1% to get a pet. Retail rates are 10 times less.
Inside these boxes there is a maguen pet waiting for you, good luck!
Elite Mobs:
Elite Bgurent
Elite Brakian
Elite Groikan
Elite Treykan
Elite Turtlelian
Elite Krajian
Elite Tardyon
Elite Kanibi
Elite Kiriona
Elite Kaiona