I am an f2p player. I have been training on akous ever since I was level 80. Since resupplying your food is easy (fish from the river in Barbarian village) and the drops from ankous are impressive, they are worth the effort. Even better, they are no where near as crowded as lesser demons or cockroach soldiers, so you basically get free dibs on them; that means easy XP. I sell a large percentage of what these ankous drop on the GE. So far, the most I have made is over 126 million from that in one week. I highly encourage f2p players to use ankous for training, and they are also good for medium level p2p players. The best part (in my opinion) is that burying the ankou bones frequently summons random events, giving you lots of free gems and runes. After you are teleported back from the events, the ankous become agressive again, saving lots of mouse clicks and making xp accquisition faster. By the way, ankous are vulnerable to the crumble undead spell. Enjoy slaughtering skeletons.