Keep in mind, Priorities change per monster. This one is one of the smartest, as well as most deadly, so he will go straight for those most dangerous, and ignore those not. If you're not on his top list, and you try to attack him or stand in his way, he will attack, but not use his super special 1-hit-KO ability. If you continue to get in his way or annoy him, your'll move up his list. If you manage to hurt him, you're bumped to priority 1 no matter what.

[b]Reference List:[/b]
Tek: Kassy (E). Naoto(Si). 
Ragna: Kurano(So). Minami(Sm).
Unrave: Kristof(Sm)(T).
The One: Slade(Si). Blade(E). Honobi(Si). Shela(E). Flemeth(E). Mimi(So).
Pharaoh: Rose(So).

[b]Priorities.[/b]
1. Sight(Si)
2. Energy(E)
3. Obvious Weapons.
4. Sound(So)
5. Physical Strength.
6. Smell(Sm)/Taste(T)

[b]Character Priority.[/b]
1. Slade and Blade, since they're both side by side and top priority abilities.
2. Naoto, because he has sight and a gun.
3. Honobi, because he has sight and a sword.
4. Kassy, Shela, Flemeth are all equal.
5. Kurano, Mimi, Rose and Kurano are all equal.
6. Kristof.
7. Minami.

Use this order to your advantage! He won't try to insta kill those of you not on the top list. Though, it might change if it turns out you're more dangerous.