Gembaiting

Gembaiting is a tactics sometimes used in the Dominions late game. It implies using a small force to trigger gem use from an enemy army. This is done to drain your opponent of gems. Over time this can impact your opponent's ability to fight.

Gembaiting has long been the subject of heated debate and strong opinions. For the sake of transparency this page will provide the exact mechanics for gembaiting. As you will discover the mechanics behind triggering gem use, aka. gembaiting, are not straightforward.

Since gems are a valuable and finite resource in Dominions the game will do a calculation at the beginning of every battle to determine whether gems should be used. This is to prevent your army from expending all its resources fighting a much smaller force, ideally only using gems when they are needed to beat your opponent's forces.

To trigger gem use from an opposing army you need to engage them with the following:

Loggy has uncovered the exact calculations the game makes to determine whether gems should be used. The game goes through the following steps;

• For each unit on the map that will be in the battle:
  • Calculate chassis value. Keep a count of total friendly chassis values and hostile chassis values.
  • If hostile:
    • If the unit is not a commander, has retreat = 0, otherwise:
      • If the commander is gone berserk, has retreat = 0:
        • If commander is scripted to retreat and is scripted returning in their first slot, has retreat = 2
          • If commander is simply scripted to retreat, has retreat = 1
          • If commander has either kind of returning on damage, has retreat = 1
          • Otherwise, has retreat = 0
    • If the unit is a commander and has retreat is not 2:
      • Calculate the total of this commander's non-holy magic path levels. If has retreat = 1, subtract 2 from this, to a minimum final value of 0.
      • Add this value to the total number of hostile magic paths
      • Add (this value * 15) to the hostile total chassis value
      • If the total number of non-holy magic paths is nonzero:
        • Calculate (total number of non-blood gems) + (total number of blood slaves/2, rounded down).
      • If this value was greater than (total number of non-holy paths * 5), set it to (total number of non-holy paths * 5)
      • Add this value to the total number of hostile gems.
      • If total nonholy paths (as calculated above) is 4+ and the number of gems > 0:
        • If (a random number 1-3) + 4 ⇐ nonholy paths + gems, trigger gem usage, regardless of anything else.
      • If has retreat is 0:
        • Look up the number of items carried by the commander, add it to the total number of hostile items
        • If (a random number 1-2) + 3 ⇐ number of items, trigger gem usage, regardless of anything else
• If the total number of hostile magic paths calculated above is 10+ and the total number of gems calculated above > 0, trigger gem usage.
• If total gems + (total items * 3) + total paths is 16+, trigger gem usage.
• If (total hostile chassis value + 2) * 5 >= total friendly chassis value, trigger gem usage.
• Otherwise, don't.

"Retreating" is defined by:

• Gone berserk always means you are considered to have no retreat
• Having returning or vortex of returning (or a modded spell with the same effect number) in the FIRST scripted slot only
• Being scripted to retreat
• Having any kind of returning on damage effect (ritual of returning, ring of returning…)

If a given commander is considered to have a means of retreating:

• Its items don't count
• Its non-holy magic paths are considered to be 2 lower than they really are, to a minimum of 0

The number of gems carried by a commander is considered to be at most (non-holy magic paths * 5). Blood slaves count half, before the cap.

Considering these things, gem usage is triggered if any of the following are true:

• (hostile chassis value + 2) * 5 is greater than the friendly chassis value (this is not easy to calculate, but accounts for most cases where PD triggers gem usage)
• There is any number of gems (so long as it isn't 0) and a total of 10+ non-holy paths across all hostile commanders
• Total numbers of hostile gems + (items * 3) + non-holy paths is 16+
• Any single mage, providing it has some gems and 4+ non-holy paths, has a ((paths + gems - 2)*33)% chance to trigger gem usage
• Any single commander has an ((number of carried items - 3)*50)% chance to trigger gem usage

At round 8, enemies will start spending gems normally.