Progression is the advancement that pieces of the same Design or Equipment make when combining, both the individual advancement of each combination to the next Tier, and the flow of pieces along the Design or Equipment hierarchy as a whole.
The majority of progressions are made by combining two consecutive pieces. Once this progression is seen, it can also be seen that each piece has two 'jobs' to perform: to combine with the preceeding Tier to make the Tier above it, and to combine with the successive Tier to make the Tier above that. However, there is a very significant number of combinations of same-Tier pieces or even 'volunteers', that either interrupt or replicate parts of the progression.
For the purposes of this guide: Volunteers, Abdicators, Jacks, Lazy, Self-promoters and Usurpers
Volunteers are pieces that combine with parts of the progression other than the succeeding Tier. If the job they do is left undone by an Lazy or Abdicator piece, they are also Usurpers. If they do not do their normal job, they may additionally be Lazy pieces or Abdicators themselves. They are worth noting as pieces to avoid or exploit; they pose challenges in changing tiers, and afford opportunities crafters to make potentially more useful pieces, raise tiers or even lower them by morphing pieces into Volunteers or keeping them around for later use.
Lazy pieces do not combine with any successive tiers as in a normal progression. Cabasset does not do the job of combining with the higher Tier Sallet, (a similar Abdicator), and the job is not done. Cabasset and Sallet are armor pieces that simply do not do one of their two jobs. Neither is there anything to replace these jobs, namely, to make a Barbut. No helm armor pieces combine in a progression to make a Barbut, although of course there are many Morphs of other armor equipments or Mismatches of Helm equipments that do. In this case, then, there is both a Lazy and and an Abdicator, and no Usurpers to take their place.
Abdicators do not combine with the preceeding piece. Their 'job' may have been 'taken' by a Usurper.
Usurper is the piece that 'takes' an Abdicator's 'job'.
Jack or Jack of Trades: Usurpers that can perform multiple tasks are useful pieces to have around, and are called Jack of Trades, or Jack for short. Another way to remember this is that they 'jack' (short for hijack) the other pieces' jobs. Breastplate, for example, is the ultimate Jack. It combines with Cuirass to make Segmentata, with Segmentata to make Scale, with Scale to make Brigandine, and with Brigandine to make Plate.
- Self-promoters combine with themselves to advance in Tier. They can replicate a job or be true usurpers.
This can be combined with strategies for gaining affinities and classes. Rondanche gloves are more likely to be hit, and therefore gain affinities and classes more easily. Rondanches are minor Jacks, but can be plugged into a progression or morph to make multiple types of armor. Rondanche is a replicator, that combines in a normal progression with Plate Glove to make Tilt Glove but also combines with Freiturnier to make Fluted Glove. This replicates the job that Tilt Glove would have had if it were not itself a Self-promoter.