At step 8 of the Pre-Game Sequence (after Spell Selection), each unit with Combined Strength may be merged with a unit from one of the unit entries in brackets (X), forming a single unit called a Compound Unit. No unit can be merged with more than one other unit. In this context, the unit with Combined Strength is referred to as Guest Unit and its models as Guest Models, and the unit it is merged with is referred to as Host Unit and its models as Host Models.
Guest Models lose any Champion upgrade and Banner Enchantment until the end of the game, and, while part of a Compound Unit, they gain Fight in Extra Rank.
Guest Models follow the rules for Matching Bases (see Front Rank), with the exception that Infantry Guest Models do not have to be placed as far forwards as possible, while non-Infantry Guest Models must always be placed in the first rank, possibly pushing back other models with Front Rank.
The original units of a Compound Unit are treated separately for the purpose of Victory Points. For all other purposes, each Compound Unit is treated as a single unit. Host and Guest Models in the same unit do not share a common Health Pool even though they all are R&F models of the same unit. Instead, each group has their own Health Pool (lost Health Points are never passed between the Health Pools, and any excess Health Point losses are ignored). Guest Models are not forced to choose the same Close Combat Weapons in close combat as the Host Models in their Compound Unit.
Distributing Hits: For the purpose of distributing hits onto a Compound Unit, Guest Models are considered as Characters with a different Type/Height combination that all share the same Health Pool.
Allocating Attacks: Swirling Melee cannot be used against Compound Units. Otherwise, Close Combat Attacks can be allocated as normal towards different Health Pools in base contact. Alternatively, R&F models that could allocate Close Combat Attacks towards any model in the Compound Unit, and R&F models that could not allocate Close Combat Attacks due to models in Duels, may instead choose to allocate Close Combat Attacks towards one of the following:
• The Health Pool of the non-Champion Host Models.
• The Health Pool of the Guest Models; these Close Combat Attacks suffer −1 to hit unless one or more Guest Models are in base contact with the attacker.