A unit of Pikemen upgraded to Aventuro's may be combined with models of Rodeleros to deploy in a Tercio Formation at the start of the game. This will then be counted as a single unit for all purposes. The number of Rodeleros can range from a minimum of five models to a maximum of half the number of Aventuros (rounding up). The points cost of any Rodeleros counts towards the points total of the same unit of Aventuros they are purchased with. The Rodeleros may not purchase any additional options.
The forward ranks of a unit of Tercio are always made up of Rodeleros (as well as any Command Group models, which have the same equipment), and all Rodeleros must be placed as far forward as possible. The subsequent ranks are entirely made up of Aventuro Pikemen. In combat, all Aventuros that are eligible to make Supporting Attacks can do so as normal.
During the game, remove casualties from the back as normal. It is assumed that the pike-armed models step forward and discard their pikes to pick up the swords and shields of the fallen front rankers. Only when all Aventuros have been killed, can casualties be taken from the Rodeleros.
Units of Crossbowmen or Handgunners within 3" of a unit in Tercio Formation may lend them support fire if the Tercio is charged to its front. This works out like a normal Stand and Shoot reaction, except that they do not suffer -1 To Hit for shooting at a charging enemy.