pc3ed wrote:ah ok so the squad leader has to have.....which weapon?
Automatically Appended Next Post:
basically i was gonna buy this
https://www.ebay.co.uk/itm/234752689661
but I wasn't sure if I need to make any physical alterations or changed to fit the havocs with mark of slaanesh and 4 lascannons
Champion can have a few different small ranged weapons, your eBay link shows a havoc champion with melta gun which is legal. The champion could also have a plasma gun, flamer, bolter, or plasma pistol.
The codex will show you which options are legal. You can also check an online reference like Wahapedia
https://wahapedia.ru/wh40k9ed/factions/chaos-space-marines/Havocs
Or you could try a program like Battlescribe with which to write army lists and see what options are available.