Your game is automatically saved after successful completion of each stage. As direct consequences:
Both successes and defeats are counted even if you Quit without Saving
Many changes to your game, inventory and/or character are permanently saved, so make sure you're not testing or doing anything you'd regret to save after. The full extension of these changes is still untested, but:
Gold and XP are kept
Trained skills (and probably Powers) are not
Events (like some quests and buying tokens from raffles) that are confirmed upon Saving, are confirmed.
Quests unsaved are untested
Some items (particularly, items picked up during the stagge) are not saved.
If you fail a stage, the failure is recorded forever, but the rest of the values of your character are loaded from your last SAVE point. This would allow you to replay the PG stage, but as this would decrease your AT reward, that's strongly discouraged, unless playing with a test character.
In any case, provided you've gotten something interesting and/or have scored a victory, you'd better SAVE manually to make completely sure all your progress is kept.
The rewards are Adventurer Tokens: Proving Grounds are one of the main means to earn them.
The number of tokens depends on your character's success: If you have 100% success (in the first rank), you will get the highest number, while if you score below 50% (the tenth rank), you will get the lowest (but you will still get some!).
Success is measured in how many times you are defeated (most times it means killed) during the whole Proving Ground.
Separate counters are kept for each PG, so you can get 100% in one of them and 50% in another one.
You can also get substantial Experience rewards, regardless of how well you do - as long as you complete the PG. On some Proving Grounds, there are smaller XP (and sometimes gold) rewards at the end of each adventure.
A lethal band of masked raiders, who fight with the skill of master swordsmen...a horde of savage forest trolls thirsting for battle...a silent mage, his face concealed and his hands wreathed in dark flame...a quiet frontier town marked for destruction...and you...lucky you
Recommended MR/SP: 60-70 MR, 70-80 SP. Hardest required combat will be 9+ at MR 70, although there are optional 9+ at MR 75 combats
Jirig Ayroth is better known throughout the realms by his infamous moniker, 'The Troll Hunter' When by chance you become involved with the legendary monster slayer and his rugged band of huntsmen, you soon find yourself in for more adventure than you ever bargained for...
Recommended MR/SP: > 110 MR to complete all optional combats, > 110 SP
Legends from a bygone era, the three brave adventurers who constitute the fabled band known as the Silver Crest now maintain a litany of aches, pains, and complaints nearly as long as their list of illustrious deeds. Perhaps you can help restore the Crest to its former glory -- not that they need any help, mind you -- I mean they're as good as they ever were -- better, in fact -- just so we're straight on that...
From the dangerous shores of Saarngard Isle to the embattled streets of the powerful and remote city-state of Kardsen, you find your fate, and those of all the free nations of the North Broadlands, entangled in a sinister web -- a deadly snare spun by a faceless enemy.
Recommended MR/SP: No less than MR 180, though 200+ would not be overkill. You can probably get through the toughest fights with powers. As to SP, the higher the better since this PG is full of consecutive tough fights (190-200 SP is probably safe).
35+ NvR is advisable. There are several lvl 80 power and skill checks. But the most essential are lvl 70 Fortification and Shadow Magic. Restoration should be high since you'll rely heavily on it during melee sequences.
Originally, Proving Grounds were a means to compare your proficiency to other adventurers, and only available for a limited amount of time. Rather than the sagas they are now, they were semi-regular events that occurred every so often.
On February 2007, all the Proving Grounds became available to replay for anyone who had not completed them, or only partially completed them. From that time onwards, any player can play them as part of the normal content of the game.