What are their purpose? Is it more worth it to sell them or turn them in to the Mage? What do you get if you turn them in? I have 20 in my vault and I'm not too sure what to do with them!

You can wear them, turn them in, or accumulate them in your inventory for Achievement.

The Element Mage is just outside the Skelly pumpkin patch in Shadowglen. He will give you either shards or tomes. Shards are weapons in the potions slot, tomes are books and stat-boosters.

Thank you very much for the information. What is the most worth it, turning them in or selling them? Sorry if that's a stupid question, I've only been playing for 3 weeks.

mage amulets are worth ~400K Shards are worth nearly nothing. Tomes are worth several million (currently 3.25, but this is variable)

You get around 1 tome for 6 or 7 amulets. If you're lucky you can make more turning in amulets and selling tomes. I think, though, that amulets sell faster than tomes, you make a little less, but its quicker.

Of course, if you want to use the tomes to improve your pet(s), then you definitely want to turn them in.

thank you, that's really good information. I'm currently training my pets up for battle - what do the tomes do?

you can read about them on SubetaLodge, Mage quest tomes Link

depends entirely on how weak you pets are now. If they are less than tier 6 in stats it might be better to buy CSC and autotrain instead of boosting with the same amount of currency.

Thank you both ^^