EvilLoynis: I have to say this about multiclassing. The only class that is worth it to do this with is the Commander Class. To many of the others have just incredible skill lvl 4/5 bonus's that you cannot get without going pure.
It's true that pure classes are never a wrong choice, but there's more to consider than level 5 skills. Different stat maximums lead to sometimes big differences in maximum health, stamina, spell levels and unit levels. Warrior multiclasses tend to not have to worry about stamina, Scout multiclasses except Com/Scout can all use the deadly stamina diversion / mass slow combo, plus pathfinding 3 is better than most level 5 skills. Then there's also the ability to use better equipment.
Some more notably good multiclasses:
Warrior/Scout: 2nd best melee and ranged damage due to massive poison damage in one package, pathfinding, can use diversion combo, can be leveled up to 20 extremely quickly going solo.
Warrior/Wizard: once again very fast leveling, wizard skills complement the Warrior very nicely, soul stealing and various buffs can keep him alive very well; mass spells, invulnerability, reincarnation, teleport, word of life, vampirism - all with +3 spell duration. Wizard/Warrior is probably even better (2 level 4 spells, could cast both invulnerability and reincarnation on himself), but slower to level. Bigger health stat also means much more stamina for costly spells.
Wizard/Commander: +spell duration and medium armor, better than Com/Wiz.