diablo-3
When I go to change my quest, there are specific Quests I can start from
How can I tell in-game when I've completed one of these Quests, and started the next one?
I dislike quitting my current game to go play with someone else, only to return and realize I have to re-do some quests again because I stopped in the middle of a quest chain
As of a recent beta patch, runes are no longer items that are dropped. Instead they are basically skill modifiers that are unlocked as you level up. Each time you level up, you will unlock new skills and/or rune choices that affect your existing skills. You choose a certain number of skills, and a corresponding rune for each, to equip as your skill set. Each skill can have up to 6 different rune versions of it, but you must select which one you want to have equipped at any time. There are no longer different levels of rune abilities, it is simply a matter of having it unlocked or not.
You will not lose the gear that you have gathered.
You will lose save progress if you start at part 1, you can go back to the quests you already done (In your example 7 to 9).
The way the party system works is that you always enter the game at the level that the host is playing at. If they are further ahead of your character personally you will join them at part 7 (in your example).
When you go back to your own personal game, you can start back at part 1 but it will prompt you to save over your spot in the game. You can continue on from part 9, but you lose out on the story line in between.
What you can do is have your friend join you in your game and help you kill the butcher and jump ahead after that is done.
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Best Answer
One way to be sure your progress is saved is to keep going until you reach a main quest with a new name. The quest name is shown both in the quest log (J) and on the list to the right.
As for the substages on each quest (the ones listed under "change quest" at main menu), I don't know a way to tell when you've reached them without knowing beforehand where the breakpoints are in each quest.