Roster

The Roster System is one of the important side-components in Era of Chaos that can significantly improve a player's total power. While not the most intuitive functionality, it is a rather cheap when compared to Artifacts, and therefore a very important tool (but not only) for Free 2 Play players.
Each unit has two defining characteristics relevant for rosters:
* A Faction (Castle, Rampart, Inferno etc.)
* A Class (Defense, Caster etc.)
For each possible individual category in either Faction or Class, a specific Roster exists.
Each Roster has a number of slots to which units with a matching characteristic can be assigned to. 
=Unlocking Rosters=
Rosters are automatically unlocked when the player reaches a specific level. Level 24 unlocks the Roster system with Castle and Charging rosters. Every subsequent 2 levels a new Roster is unlocked in the following order: Rampart, Ranged, Stronghold, Defense, Necropolis, Caster, Inferno, Offense, Tower, Conflux, Dungeon, Fortress, Cove. At level 50 all rosters are unlocked.
==Roster Slots==
Each roster automatically starts with 3 open slots. Up to 3 more can be unlocked by either attaining specific VIP levels or reaching the required Player Level. Each additional slot costs Diamonds as follows:
Slot	VIP Level	Player Level	Cost
4th 	V6 	45 	200
5th 	V8 	55 	500
6th 	V10 	65 	500
It is strongly recommended to invest in your primary rosters by unlocking additional slots.
Class Rosters are generally more flexible as the possible unit selection is larger, while Faction Rosters need to be focused depending on what factions are used in your formation.
==Upgrading Rosters==
Like units, rosters have tiers and can be upgraded to higher tiers by spending Roster Runes.
You can obtain Roster Runes from:
* Guild Store - specific Roster Runes in exchange for 
* Completing Phantom Realms - 2x Expert Roster Runes boxes once a realm is completed
* Plane Store - 5x Roster Runes boxes in exchange for 
In order to upgrade rosters, it is therefore highly recommended to always complete your daily quota of 5 Phantom Realms.
Higher tiers boost the overall roster Score by a specific percentage.
===Rarity Rosters===
The newly added Rarity Rosters have different costs from the rest of the Rosters, and require two types of Roster Runes:
* Specific Roster Runes - just like the other Rosters, there are "R", "SR", "SSR" and "Commander" Roster Runes. These can only be obtained from the Guild Store. The required number per tier is also significantly greater.
* Special Roster Runes - this is a special type of Roster Runes that are required by all Rarity Rosters in addition to their specific Runes. This count seems to match that of the Regular Runes. To obtain them, one must "exchange" specific runes into from the Roster screen (for a 1:1 exchange rate).
===Tiers Numbers===
Tier 	Regular RosterRunesSpecial Runes	Rarity Roster Runes	Bonus %
Common 	- 	- 	+0%
Green 	2 	10 	+3%
Green +1 	4 	20 	+6%
Green +2 	6 	30 	+9%
Green +3 	8 	40 	+10%
Blue 	12 	50 	+12%
Blue +1 	16 	60 	+15%
Blue +2 	20 	70 	+18%
Blue +3 	24 	80 	+21%
Purple 	30 	100 	+24%
Purple +1	36 	120 	+27%
Purple +2	42 	140 	+31%
Purple +3	48 	160 	+35%
Purple +4	56 	180 	+39%
Purple +5	64 	200 	+43%
Orange 	76 	?? 	+47%
Orange +1	88 	?? 	+52%
Orange +2	104 	?? 	+57%
Orange +3	120 	?? 	+62%
Orange +4	140 	?? 	+67%
Orange +5	160 	?? 	+72%
Red 	200 	?? 	+77%
Red +1 	250 	?? 	+82%
Red +2 	300 	?? 	+87%
Red +3 	? 	?? 	+92%
Red +4 	600 	?? 	+97%
Red +5 	900 	?? 	+102%
==Roster Groups==
Each specific roster assignment will belong to a Roster Group. By default you have only one Roster group unlocked for free. You can further unlock up to 7 more. To unlock the first extra group you need to pay 200. Every subsequent group costs 50 more than the previous. (hence they cost from 200 up to 500)
Roster groups are basically a way of saving your roster configuration and easily switching between. However, unlike Artifact Groups which can be assigned to specific heroes and specific scenarios of the game (Arena, Campaign, Main Story etc.) and will remain memorized, only one global Roster group can be active at a time and will impact all heroes and all scenarios in the game. Therefore investing in groups will save you the time to switch in-between configurations but will offer no other advantages and are more of a "lazy" investment".
=Roster Assignment=
Each Roster has a score assigned to it. The greater the score, the more it will benefit your units.
To increase a Roster's Score, you need to assign units to it that share its characteristic (in Faction or Class). A unit can be assigned to at most one Roster. For example, a Giant can be assigned to either your Tower roster, Caster roster, or neither of them.
==Unit Roster Score==
Every unit has a specific 'Roster Score' that depends on multiple factors. The more developed a unit is, the bigger its score. The bigger its score, the more it will contribute to the Roster it is assigned to.
Below you can take a look at how each individual factor influences the score. Keep in mind though that it's sufficient for you to know what are the highest impact ones and focus on those if you want to improve your rosters only (but not use the unit in your actual formations).
Factor 	Bonus 	Maximum Value
Base Score 	120 	120
Rank (Stars) 	100 	600
Rank (Sub-Nodes) 	5 	45
Awakening Star 	100/20/30/40/50/60	300
Tier (Color) 	35 	560
Unit Level 	3 	330
Equipment Level 	1 	440
Skill Level 	8 	120 (without Emblems)
Talent Level 	30 	510
Extra Equipment Bonus	5 	?
Note that unit Potential does not influence the Roster score in any way.
The actual formula to determine the final bonus is as follows:
% Bonus = Score / 16600
Example: A roster with a score of 1884 leads to a base bonus of 1884 / 16600 ~= 0.1135 = 11.35%. If that roster is a Purple +5, it is further multiplied by the bonus, namely 11.35% x 1.43 = 16.23%.
==Roster Bonuses==
As already mentioned, a roster will benefit all your units of that particular Faction or Class regardless if they themselves are assigned to a Roster or not. For example, if you have an Imp that is not assigned to any roster, it will still benefit from both the Inferno and Defense rosters.
Each roster adds two benefits to the units, that both scale with that roster's Score and have an equal +% value: +% Attack and +% HP.
Let's take another example. Assume we have an Angel with 300K HP and 10K ATK. We have a Castle roster with a bonus of 33% and an Offense roster of 17%. Both these benefit our Angel, so in the end we get a +50% bonus from rosters. This will increase our Angel's HP to 300K + 50% = 450K, and his ATK to 10K + 50% = 15K.
=The Roster Optimization Game=
The tricky part about Rosters is to get the bonus that best improves your current team (and your overall score). Here are some of the aspects of the "Optimization Game" to consider:
* Each roster has a limited number of slots and a tier (hence +% bonus). 
* If your rosters have the same tier, the tier itself will not influence the optimal assignment.
* Each unit can be assigned to one of its affiliated rosters or no roster at all.
* Each unit has a specific roster bonus that is not roster dependent. (but will be amplified based on the roster's tier)
* Rosters that have no affiliated units in your formation can be completely ignored.
* The more units you have affiliated with a roster, the greater it will benefit you. This makes formations with one or two factions only much easier to boost via the roster system.
==The Greedy Approach==
Here is a rather simple and effective method to get a pretty good power boost from your roster by hand, without having to rely on any tools or complicated calculations. It will most likely not provide the optimal (best) solution, but may be good enough for many.
* Start by emptying all your rosters. We want to start from scratch.
* Define the units that go into your formation.
* For each roster, count the number of units in your formation that would benefit from it.
* Remove all rosters that have a unit count of 0. They will not benefit you so we don't bother with them.
* Take the remaining rosters in order, starting from the highest unit count and ending with the least. If there are multiple rosters with the same count, take them in any order you want. Perform the next two steps for each of them.
** Look at all unassigned units available for the roster. If there are more slots than units, just assign all available units to the roster and you're done.
** If there are more available units than open slots, assign the ones with the highest scores.
==The Hungarian Method==
There is a Google Spreadsheet that can perform this optimization automatically and save you a lot of time. You may check it out here (works best from a Desktop or Laptop).
==Multiple Teams Formations==
For some very specific scenarios (like Trial of Angels or Battle of the Gods) you may be forced to use the same Roster Group for multiple teams. You can extrapolate to this scenario simply by putting together all units in all formations and optimizing as if you had one big formation.
If you are very lazy you can even do that for completely different game modes where in theory you could switch in-between groups. This will of course lead to less optimal results but sometimes for scenarios like the Campaign it's "good enough".
Note: Some veterans consider that some units benefit more from the roster than others. For example, support units don't necessarily benefit much from a damage bonus - but HP is important for them not to die too fast. Unless you are an expert in your server's meta and absolutely confident in these super fine tweakings, focusing on maximizing your score will probably lead to the best result for you.