Just an idea I had as an alternative to the standard Sentry deployment rules. It's not meant to replace them - that is to say, I don't believe this is "better" than the rules as written. It's merely something different to try.
Nominate one of the table edges as North. The remaining edges will be East, South and West as appropriate.
The defender divides his gang as evenly as possible into four groups. For example, if the gang contains thirteen models, three groups will contain three fighters and the fourth group will contain four fighters. Each group must be assigned a direction – North, South etc. This is done without the attacker knowing which models are in which group.
The attacker now nominates which direction he will attack from – North, East, South or West. The defender deploys the corresponding group of fighters as per the scenario guidelines. The remainder of his gang are not deployed immediately but may become available as reinforcements during the course of the game if the scenario allows. The attacker then deploys as per the scenario rules.
Whatcha think?
