The way magical effects are presented in a game can have a profound effect on the overall feel of magic in that game.
Magic can be explicit — eyes full of light and wonder, flame and fury, and electric fireworks showering down all around. Magical effects are seen and obvious.
Magic can also be implicit with no visible connection between the caster and target. All that is seen is an initial cause then the following effect. Perhaps there is a gesture from the caster then some sort of ill effect is noticed upon the target.
In the two movies, The Lord of the Rings and Harry Potter and the Order of the Phoenix, we have two pairs of wizard rivals and two climactic magical combat scenes.
The fight between Dumbledore and Voldamort uses explicit magical effects. You can see the streams of light connecting the two casters. It is a magical spectacle full of awe and raw energy.
The fight between Gandalf and Saruman uses implicit effects. There is nothing visible connecting the two. When one caster pushes forth with his hands and staff, the other goes flying. An invisible force is implied to exist between them. Instead of a spectacle, the combat has more of the feel of a boxing match–simple violence, but with the contact being magical instead of physical.
One way of presenting magic is not better than the other. It is more of a matter of the feel you wish to create for either your game overall or for a particular scene. Explicit spell effects can be used to create excitement or wonder, implicit spell effects used to create a sense of menace, dread, or foreboding.
Personally, for the Lankhmar setting, I believe that implicit magic is more in keeping with the feel of the stories overall.