Okay, so I've got an item that will be used to shock the block the player is looking at, but I have no clue how I can make something that even remotely looks like lightning come from the wand to the block. Any ideas?

If you want actual lightning from the sky, you can add an

EntityLightingBolt

to the

World

's weather effects.

 

If you want something like the

Thaumcraft

lightning wand, you'd have to make a custom effect.

Look at particles (e.g. sword slash). Weather lightning is an entity that can interact with other entities. If your wand's only effect is on a known target block (and the lightning is merely a visual effect) then particles may suffice.

 

Also look at how a fishing rod casts its line (and how the line is rendered).

Well, it can also be used to deal damage to an entity, but I'm already raycasting, so I can do that easily. Basically, I just don't know how I would add in the visual effect. Particles don't seem right , because I'd like to be able to render the lightning bolt spanning variable distances based on how far the target is

Botania has some code to generate lightning bolt effects using the particle system.  I'd recommend perusing that code (it's in the vazkii.botania.client.fx package), and refer to http://botaniamod.net/license.php if you want to use the code (the license is reasonably liberal).