Just a beam colored "heat ball", maybe the beam charge particle could be also be used as shield impact particle. Of course, since it won't be in Mediavps (retail wouldn't need that sort of thing), it'd be entirely up to modders what effect they put there. SCP's job ends when adding such an effect is possible (and bug-free), they don't need to worry about making the actual effect file (for testing, any would suffice). Two table entries ($Shield Impact Effect: and $Shield Impact Radius: ) in weapons.tbl would do the job. Ideally, they'd work for normal weapons, too (overriding the normal impact effect).