How does the light beam/arcane beam/lightning beam interact with multicast and cast frequency?

[Belgarion]

- If my beam 2x multi casts, does that mean I get a double damage tick for the 8 seconds or so that the beam lasts?

- If my beam cast interval is 4 sec and it lasts 8 seconds, does taht mean I get a double damage tick for the entire 8 seconds or does it just refresh the beam with no impact to damage?

[Belgarion]

In the same vein, what happens if I multi cast an empowering spell or if I recast another empowering spell before the last one expires? Double everything every time or just refresh?

[Eudicots]

Multi-cast on beams causes another instance is just be cast on top of each other. The same is true for combustion and flamethrower.
Cast frequency just makes you cast this skill more frequent reducing its cooldown.

[HoneyDrake]

Any form of attack stacks/gets cast again. So you have overlapping beams for example.

Any form of buff, like Might, gets "refreshed". Multi cast is worthless on them.

You will just cast a new beam once the cooldown is over, old one will not magically disappear

The best spell which you can check how "beams" work is the unique spell of Deathknights. The one going in circles around the Deathknight. It will become easy to tell how beams work.