I think I ended up in 5th place for my league.
I purchased an Energy pack...and started with a group skirmish.
When I won the 1000 energy prize, I just kept going. I started using the auto-recharge feature and picked all of my guardians that needed upgrading.
I ended up with an additional 142 basic summoning bonds, I Epic bond, and get this....1..Holy Bond! I was speechless:)
Both the Epic and Holy bond gave me two level IV Guardians (no surprise there) I believe there was a few other prizes, like some Epic bonds (which again gave me some grade III Guardians)
So..good news is that I got 1 grade 4 skill stone, some grade III skill stones, a load of basic bonds (total of 378 as of this writing) and the method of using the skirmish feature to boost your Guardians up.
I believe I won an additional Grade 4 skill stone.
All in all it wasn't bad-the group skirmish on auto (when you have lots of energy) is good. If you don't, then you will have to sit for hours.
I believe I was lucky enough to get the energy pack, then the prize of 1000 energy. If you didn't purchase an energy pack, be prepared to spend long hours on the game.
Next Guardian havoc challenge I will be sitting it out as I feel it is not worth it. Truth be told, I would rather spend for an energy pack or purchase bond/emerald package than spend my time on this. It all seemed so inconsequential.
Regards & respect