Training Invention & Slayer to 120

Hey guys, basically I came back to the game after 7-8 years and now I want to train slayer and invention to 120. Both my invention and slayer lvls are 100 (got invention from fishing afk). Now I need help with figuring out what armor and which weapon is best for invention (I`ll be using legacy not EOC), which perks to use and which slayer master to use (prefer more AFK tasks). I have about 300m cash as of right now and don't really want to spend it all since my bank is worthless. Edit: I am maxed out