The ruler has absolute power over his units. He literally can end them with a thought. All subjects are forced to serve his will due to Natural Thinkamancy. The ruler decides what cities produce, can promote units to warlords, and can designate an heir. The ruler appoints the Chief Warlord, but can command his Side's units if necessary.
 Becoming a Ruler
An heir will become ruler of a side immediately upon the ruler croaking or abdicating. If the new ruler's side owns at least one city, then the side continues as before. If it has no uncontested cities of its own, then the side falls and the would-be ruler becomes a barbarian.
 End of Rule
A ruler's rule ends when they die, turn to another side, or abdicate their rule.
A ruler whose rule ends without an heir causes their side to fall. Cities become neutral, and freeze in time. Units left in those cities do not experience turns, and cannot act unless the city is attacked. Units in the field disbandErf-b1-p098bsummer-updates-043 .
 Ruler Senses
Ruler sense is a form of Natural Thinkamancy that allows them to know the exact number of units on their sideIPTSF Text 25, where they are, and their pointsIPTSF Text 26. It has been shown that a ruler can know where their Chief Warlord isErf-b2-pT49. This does not apply to natural allies, however.IPTSF Text 45
 Proposed Canon
 Known Rulers and their Heirs
- King Banhammer (croaked, succeeded after a significant delay by Royal heir, Princess Jillian Zamussels)summer-updates-037
- Jillian Zamussels (current Queen)
- heir: In production, should pop in 81 AW.
- King Saline IV (croaked, succeeded by Stanley the Tool)
- Stanley the Tool (current Overlord)
- heir: none
- King Flintlock the Voluble, King eigthy thousand turns ago.
- King Headboard, King prior to Slately
- King Slately, King prior to Tramennis
- previous heir: Prince Ansom, Chief Warlord, croaked in the Battle for Gobwin Knob.
- previous heir: Possibly Prince Ossomer, Chief Warlord, croaked and decrypted by Gobwin Knob near the capital of Jetstone.
- King Tramennis (current King)
- Don King (current King, succeeded King County at the age of 15 turns)
- King County (previous King, croaked)
- previous heir: prince, unnamed son of Don King, croaked, presumably as a result of an attempted coup against Don King
- previous heir: princess, unnamed daugher of Don King, croaked
- heir (Designate): Caesar Borgata, Chief Warlord and Viscount of Vitalis.
- potential Royal heir in production, but not yet popped.
- Queen Bea (former Ruler, croaked)
- previous heir: Princess Cruz, croaked, Decrypted by Gobwin Knob, and destroyed)
- Overlord Firebaugh (Wanda's father, croaked)
- Overlord Wanda Firebaugh (Only ruled for a few moments before her side fell)
- Overlord Lex Doothis, Overlord prior to Judy Gale
- Overlady Judy Gale (departed Erfworld using the Arkenshoes, succeeded by Olive Branch)
- Overlady Olive Branch, croaked
Confusion on the name of this position came from Parson learning facts incrementally. Initially, he was mostly familiar with Stanley, an Overlord, so Klog 5 referred to Overlords. Later, he apparently learned that Overlords are Rulers that are not Royal, and so the more general term Ruler is introduced in Klog 10. This change in terminology gave the impression that the two terms were synonymous. Rob Balder has confirmed that Ruler is the correct term, and that Overlord is merely a Ruler that is not Royal.
The Heir of a side is usually the Chief Warlord and vice-versa. From the known heirs, most were also known to serve as their side's Chief Warlord at one point or another. It is not known whether or not Princess Cruz or Don King ever served as Chief Warlord, but given the circumstances under which he was popped, the latter probably did not.
It is worth noting That Jillian and Ansom were popped as heirs and Ansom was later (possibly immediately, possibly only after gaining a certain number of levels) promoted to Chief Warlord; which means for a time, at least a portion of one turn, possibly many turns, the Chief Warlord was not the Heir.
Conversely, Stanley was promoted to Chief Warlord first and then after a while was promoted to Heir, due to his victories with dwagons. Had King Saline IV popped an Heir instead, as is common, he likely would not have made that Heir his Chief Warlord - at least not right away.
Wanda Firebaugh was popped as an Heir, but was not initially Chief Caster of her side, though she was eventually promoted to that position. She is also an interesting case because she was the first caster confirmed to have ever been either an Heir or a Ruler. All Rulers and Heirs previously known had been Warlords, though other caster rulers have been revealed since then, such as Charlie, Olive Branch, Bell, and Blair. It is as yet unknown whether other unit types can become rulers.
It makes sense to combine the two positions: a chief warlord is the second most important unit of a side and has a lot of influence in military and diplomatic strategic and acts in many ways as replacement for the Ruler. Also the chief warlord is by definition and natural Thinkamancy the most loyal person and therefore least likely to plan regicide.
However, Chief Warlord is an appointed position, and any Commander can be given the job. Strategically speaking, the best choice is the person with the best mind for tactics, and/or the highest Leadership bonus, since his bonus extends further than anyone else's.