i've noticed when i get attacked or when i attack a Town Shiled is deployed (at no cost when it was on myself) for 12-16 hours. In an 9 hours period i was attacked twice.
I am wondering when this shield is deployed after an attack or if it's possible for 2 people to attack one town at the same time.
The automatic shield is deployed when certain conditions are met:
When 40% of your village or your Town Hall is destroyed in a raid, you will get a 12-hour shield. When 90% or more buildings are destroyed you will get a 16-hour shield instead (these two shields cannot be stacked together).
For the most part, you'll see shields deployed when you lose a battle, as opposed to a successful defense. There are some corner cases (ie, Town Hall intact and 40-49% of the buildings destroyed) where you can both win and get a shield.
As far as I know, there's only one raid allowed on your town at a time. Thus, if you trigger an automatic shield as a result of a raid, you should be granted immediate protection against further raids.
Well this was posted at the end of November in 2015, so it's more recent.
Basically, 2 conditions have to be met.
The attack has to do more than 30% damage to your base. Town Halls no longer give you a shield by themselves.
So if someone only destroyed your Town Hall, you would not receive a shield.
You also get:
A 12 hour shield at 30% A 14 hour shield at 60% A 16 hour shield at 90%
Heroes count as 25.
Ex.
If the defending player is TH7, then the max army camp level is 6, which is 50 / camp, plus an hero, which is 25.
So an attacker must use 225/3 - 75 troop value - Even if they don't have a hero or their army camps aren't level 6.
