Welcome to Librarium Online!
Is the following list good for a hordes/warmachines competition (at local game shop)?
6 X Shredder
I might switch 2 shredders for a Seraph, not sure yet.
it's up to you on how you play with your army because i use Thagrosh because i run beast heavy and also i don't like how Lylyth plays or any or her spells but that's just my opinion
your army seems to also have a fury heavy army so i recommend a Sheppard
Question: Is using a Plasma rifle to kill a fly overkill?
Answer: Nevah, the fly was in the way when i was melting some Death Guard!