Gate stances: what they do, costs and counters

Short answer

Each gate Holds, Sallies out or Falls back. Hold takes 20 % less from Brutes, Sally out hits Runners 80 % harder, Fall back saves 40 % of the loot.

What it does

Every gate has a stance, and changing it is free. Hold is the default. Sally out sends the road's guards and your reserve charging from the first second. Fall back pulls the road's guards back to the keep to protect your stock.

They work like rock-paper-scissors. Sally out beats fast, fragile Runners. Hold beats Brutes, which lose their edge against a gate braced for them. Fall back is the answer to Climbers, who skip your walls anyway: raiders carry off 40 % less, 60 % less against Climbers.

Stance

Stance	Effect
Hold	The default. The gate and walls take 20 % less from Brutes.
Sally out	Guards and the reserve charge out: 40 % more damage, 80 % more against Runners, but they take 30 % more hits (60 % more from Brutes).
Fall back	The road's guards wait at the keep. Raiders carry off 40 % less (60 % less against Climbers), but the gate takes 30 % more damage.

What answers what

Attackers	Emplacement	Stance
Runners	Spikes	Sally out
Brutes	Tar	Hold
Climbers	Ballista	Fall back
Shamblers	Any (small bonus)	Hold

Tips

Change the stance when the Watchtower reveals what's coming; Prepare defense suggests one.
Sally out against Brutes costs guards; switch back to Hold.
Fall back when you'd rather keep your stock than your guards.