Familiarisation (x3) combined with double drops in chaos tunnels (x2) = x6
DO IT! Do familiarisation and then run to the chaos tunnels and go to waterfiends.
Check the runescape wiki if you don't know how to do any of that.
Idle in "Hughs Horde" fc to find an active summoning altar.
This is what I got in 38 minutes:
