any of those landmines can be added with other elements to combine more effects, like water to make you wet or fire to ignite them as well.
Shield + any element cast on self, will make you immune to that element for a while, this includes making yourself immune to healing, so be careful about that, you'll know you're immune to healing if your aura is green and then you'll probably start shouting profanities like i did when i was just trying to heal and then put a shield on
For individual strong enemies I like running far away and then quickly aiming an Arcane + Water beam at them to get them wet. After that I use Arcane + Frost beam to freeze them. The beam nature of the combination means that the enemy is permanently frozen and the beam gradually kills them =D
^Yeah, I found out about that combo just recently, and it's waaaay too much of a game breaker. No reason to do anything but that over and over again. The game just becomes too easy with that combo. For practicality, though, you could just steam+lightning+arcane and omit the rest. Faster input means more efficient input.
Shield + Earth = Rock Shell (more earth makes a stronger shell) Makes you invulnerable until it breaks, but you cannot move and casting breaks the shell. You can, however, charge up whatever nastiness you can imagine without any enemies being able to do anything about it.
Ice + Shield + Cold + Lightning + Arcane = High-damage close range aoe Casting this as aoe causes a ring of icicles to erupt around you, which chill and chain-lightning any nearby enemies. They then almost immediately explode for arcane damage. Excellent to cast from inside a rock shell, since all melee enemies crowd around the shell and get ravaged by this spell. Very nasty effect to apply to your weapon as well.