A potion saved is XP earned.
After a game in which you were particularly efficient in slaying dragons, you will now gain an XP award.
Your efficiency for a game is calculated as follows: (DRAGONS SLAIN + 4) / POTIONS USED. Results are rounded down. (A sacrificed potion counts as used.)
The awards range from 25% for an efficiency rating of 2 all the way up to 500% for a rating of 11+. The award percentage is applied to the XP earned in the game. So if the award is 25%, and you earned 1,000 XP that game, the award would be 250 XP. This award is then split up between the three heroes in proportion to the XP each hero earned that game - unless you choose to cross train, in which case the award is divided evenly between the heroes.
You can track your potion use by clicking the potion counter while in a room. Efficiency awards are only for career and campaign games, not tournaments or hunts.
Along with this change, we lowered the XP from dragons by 100.