If I use 'Ritual of Summoning' (Silver Twilight) to sacrifice all of my characters including "Professor Nathan Peaslee" (Miskatonic) and the use his ability to bring them all back including him, is this possible?

I mean, I can do a very cheap-ass recovery for all of my characters, get rid of any wounds or insanity, play almost any character for free with all these tokens and even do a loop thrice?

In any phase?

And I can also use any character card effect as long as they use 'enters play' or 'put into play'?

Is this some kind of loop hole or do I overlook something?

I mean combine this with some characters, which force your opponent to take characters back to his hand or sacrifice them and your are unstoppable.

Plus, you'll heal any exhausting, insanity and wounds. This can't be right.

Don#t forget all those tokens for another cheap character.

Yeah you can use Peaslee + RoSac like that as long as you sacrifice Peaslee last.

However, you have to get to the point where you can do that; that's turn 4 at the earliest (3 if you use a Visiting Author or another Transient card) considering how you have to resource to make that work. If that's the goal of your deck, then it's probably too slow, and is too combo-reliant and can be broken so many different ways (Support card destruction, Lodge Housekeeper, etc.) Also, you would have characters leaving play. That would allow opponents to bring in Dreamlands Fanatics and the like, and using Peaslee to bring them back allows your opponent to trigger Intervention and the Yog "triggered effects" wolf thing (can't remember it, and cardgamedb isn't working for me right now).

In short, while you can do that, it's not as overpowered as it appears at first glance. Any deck worth its salt would be able to break that combo up quick, fast and in a hurry.

Ok, it does work and is legal. That's nice to hear.

One additional question about the timing of use:

I can use it at the opponents story phase, after he has stunned/wounded/exhausted my characters to get to the stories scot-free and do a full recovery to attach to storie anyway.

But can I use afterwards (after finishing the story phas) also, to do a full recovery before my turn begins?

I have made extensive playtesting with a deck built around that combo. In about thirty games I was able to use the combo to good effect about two or three times..

I ended up removing the Ritual of Summoning (and everything from the Silver Twilight faction) resulting in a much better deck.

Of course it could simply be that my deck sucked

In case you're interested, here's the deck list (without ST): www.cardgamedb.com/index.php/CoC/cocdecks.html/_/coc-decks/liege-2011-r49