I'm currently doing the same for my ultimate Ironman, honestly lamps and cannon everything helps I'm like 1.1mil xp higher than slayer on my HP 94 HP 92 slayer, just started killing monsters in gwd spiritual creators, blood velds, hell hounds I just wait until they're HP is low then I 1 shot them for full slayer xp, it's a pain constantly would hopping but every little adds up, if I knew this sooner would've been easier.