I will note that it is possible to get infinite loops in every phase, including your opponent's phases and the between turns donate phase, due to reacting with sheepdog as way of the vassal hitting some throne room. From the throne room you can create some of the action phase loops described.
Here is a loop that uses none of the cards in the new list:
hand is crown, mandarin, your favorite treasure, horn of plenty, black market
deck is crown, mandarin, your favorite treasure, horn of plenty
play a black market
play a crown
play mandarin as way of the horse
play mandarin as way of the horse
play your favorite treasure
play horn of plenty, gaining mandarin
repeat
Yes, you're right, thank you! I thought there's no way to gain Mandarin and remove gainer from play without Capitalism, but Black Market does the opposite, allows to play a treasure type gainer in action phase. This invalidate my statement that you can't do the Mandarin trick without Capitalism, so we have to include Mandarin in the list.
In the loop you posted there are only four different named cards in play when you play Horn of Plenty, so you can't gain Mandarin, but I think it can be fixed (with Canal, for example). About this loop, however, I have a doubt: from your deck with a total of 9 cards, how you manage to control that exactly these 5 will be in your hand?
For the loop in Donate phase, you have also to trash something like Catacombs or Hunting Grounds to gain a card and react with Sheepdog. But how can you play a card with Vassal in Way of the Mouse if you still didn't shuffle your hand into your deck? (Edited: I found the answer. See post below)
I think a loop in your Opponent's phase depends on what she played, don't? So, to setup the initial conditions for loop is out of control. Anyway, I would like to know if there's a loop in opponent's phase that doesn't use any of the enablers of the new list.
Including Mandarin, the list of essential cards for infinite loops is this:
- Villa
- Cavalry
- Scepter
- Capitalism
- Gamble
- Toil
- March (I'm not sure about this, since Gamble with Star Chart seems to me to be strictly better than it for loop purposes)
- King’s Court
- Mandarin
- Trader
I would be happy if you contradict me again and show another loop only with cards out of this list. Every time you do this I learn something.
I will note that it is possible to get infinite loops in every phase
Can you think in a loop in night or clean-up phases?