Johannes Kepler, Astronomer Extraordinaire

In Prague in 1454, Johannes Kepler calculates the paths of worlds for vessels that dare to travel between them. He was born in Weil der Stadt in Swabia and learned mathematics through scholars, travelling instrument makers and celestial records far older than the Bohemian Crown. His work now brings him into the dispute between Ladislaus the Posthumous’s household and George of Poděbrady’s officers: both want charts they can trust, and neither will accept responsibility for a lost ship.

Alias – None
Gender – Male
Race – Human
Occupation – Mathematician, astronomer, celestial navigator and diviner
Religious outlook – Private; studies celestial traditions and sacred cosmologies without serving a single temple
Allies and rivals – Tycho Brahe, Copernicus, Prague’s astronomical observers and instrument makers
Enemies – None recorded
Abode/ Base of operations – Prague, Bohemia
Nationality – German
Languages – German, Latin, Greek, Hebrew, Arabic, English
Alignment – Lawful neutral
Affiliation(s) – Prague Celestial Project; astronomical adviser to rival Bohemian court patrons
Close relationships – Swabian family correspondents, Prague scholars and a small circle of trusted navigators

Kepler’s studies have brought him into contact with the remarkable instruments and returned voyage records of the Prague Celestial Project. He reads the paths of planets from observations, reconstructed star tables and the testimony of navigators who have seen the heavens from beyond Earth. His calculations show that a famous chart may point to two very different destinations, depending on the date of departure. He has begun to suspect that an ancient navigator deliberately concealed the true interval.

Kepler searches for mathematical order in the heavens, but he does not presume that any single temple or court owns the truth. His notebooks compare observations with old cosmologies and surviving accounts of the planets. He is willing to contradict a powerful patron when an instrument gives a different result, which makes him useful to fellow scholars and dangerous to those trying to conceal a failed expedition.

At present the next aethership is being provisioned while Kepler, Copernicus and Tycho Brahe argue over its departure chart. A copied record has disappeared from the university; the original shows a position in space at which an earlier crew ceased sending signals. Kepler wants an independent party to trace the stolen sheet before the ship departs under a false course.

Kepler is a reserved, ink-stained scholar who carries finely ruled charts, a brass instrument case, a long sighting tube and an enchanted telescope capable of observing faint celestial movements. His quarters contain an orrery assembled from several centuries of parts. He often forgets a meal while reducing a column of figures, yet notices immediately when someone has disturbed the order of his notes.

Johannes Kepler, Astronomer Extraordinaire

Medium humanoid (human), lawful neutral

Armor Class: 12 (15 with Mage Armor) Hit Points: 120 (20d8 + 20) Speed: 30 ft.

STR	DEX	CON	INT	WIS	CHA
8 (-1)	14 (+2)	12 (+1)	20 (+5)	16 (+3)	10 (+0)

Skills: Arcana +11, History +11

Senses: passive Perception 13

Languages: German, Latin, Greek, Hebrew, Arabic, English

Challenge Rating: 12 (8,400 XP)

Actions

Quarterstaff. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage.

Fire Bolt. Ranged Spell Attack: +11 to hit, range 120 ft., one target. Hit: 21 (6d6) fire damage.

Magic Missile. Ranged Spell Attack: +11 to hit, range 120 ft., three targets. Hit: 16 (4d4 + 4) force damage.

Time Stop. he can use an action to cast Time Stop, as per the spell.

Counterspell. he can use his reaction to cast Counterspell, as per the spell.

Divination. he can use his action to cast Divination, as per the spell.

Scrying. he can use his action to cast Scrying, as per the spell.

Identify. he can use his action to cast Identify, as per the spell.

Detect Magic. he can use his action to cast Detect Magic, as per the spell.

Equipment

Quarterstaff, Robes, Book of Astrology (contains notes on Kepler’s astronomical discoveries), Crystal Ball (used for divination), A gold necklace with a small telescope pendant, Ink and parchment, Spellbook containing various divination spells, 500 gold pieces

Abilities

Astronomer. he gains proficiency in the History skill and has advantage on Intelligence (History) checks related to astronomy.

Mathematician. he gains proficiency in the Arcana skill and has advantage on Intelligence (Arcana) checks related to mathematics.

Divination Mastery. his divination spells are particularly powerful, and he can choose to roll 3 d20s instead of 2 when using Portent, as per the Wizard’s Portent ability.

Mage Armor. Kepler always has the Mage Armor spell active, granting him an additional +3 bonus to his AC.

Lair Actions

Once per day, while in his observatory or laboratory, Kepler can use the following lair actions:

Celestial Observatory. Kepler can use his action to activate the magical telescope in his observatory, allowing him to see and hear anything within 1 mile of the observatory.
Magical Laboratory. Kepler can use his action to cast any spell he has prepared or in his spellbook, without expending a spell slot.
Temporal Distortion. Kepler can use his action to create a temporary time rift in his laboratory, causing all creatures within a 30-foot radius to make a DC 16 Wisdom saving throw or be affected by the Slow spell for 1 minute. Kepler is immune to the effects of this ability.

Legendary Actions

Kepler can take 3 legendary actions per round, choosing from the options below. He regains all legendary actions at the start of his turn.

Fire Bolt. Kepler can use his Fire Bolt action.
Magic Missile.he can use his Magic Missile action.
Teleport. Kepler can use a bonus action to teleport up to 60 feet to an unoccupied space he can see.
Legendary Resistance (3/Day). If Kepler fails a saving throw, he can choose to succeed instead.
Spell Mastery. Kepler can use his action to cast any spell he has prepared or in his spellbook, without expending a spell slot.
Eccentric Mind. Kepler can use his action to create a temporary zone of magical distortion, causing all creatures within a 30-foot radius to make a DC 16 Intelligence saving throw or be affected by the Confusion spell for 1 minute. Kepler is immune to the effects of this ability.

Note: Kepler’s CR is 12, which makes him a formidable foe for a party of mid- to high-level adventurers. However, he is not meant to be a traditional combat encounter. Rather, he is a powerful and eccentric wizard who can serve as a quest giver, mentor, or even an antagonist if the players cross him.