League
Permanent Leagues
The only permanent leagues are "Default" and it's child league "Hardcore" which has the Hardcore modifier.
Race Leagues
Race leagues are non-permanent leagues created specifically for a race event.
Leagues Modifiers
Ancestral
First introduced in S1E51. Every area has "This area is inhabited by totems" map modifier, except for boss chambers.
Blood Magic
First introduced in S1E61. All characters start with an active Blood Magic passive.
Cut-throat
TBD.
Hardcore
A character killed in Hardcore is moved to its parent league.
Lethal
All monsters deal 50% extra damage plus 50% extra damage as cold, fire and lightning. This yields a total of 375% of normal damage (100% + 50% + 3*((100% + 50%)*1.5) = 150% + 3*75%).
Multiple Projectile
First introduced in S1E53. All monster skills are supported with Greater Multiple Projectiles.
Solo
You may not party in this league.
Turbo
Monsters move, attack and cast 60% faster.