Syndra shares the voice actress of Evelynn, however, the voice actress has never been publically revealed or credited and is anonymous.
Syndra is the first official champion to directly manipulate minions and neutral monsters to deal damage to other champions, moving them around with her abilities.
Syndra's spheres appear as red instead of blue when on the opposing team. She is the fourth champion to have team perspective based particles, with the third being Draven, the second being Cassiopeia and the first being Singed.
Syndra is the second of the three dark themed Ionian Champion, the other two being Varus and Zed. She shares a light themed skin with Varus and Aatrox.
Syndra's dance is based on the choreography for the song Hoot by Girls' Generation (소녀시대: So Nyeo Shi Dae), a popular Korean girl group. A side-by-side comparison video can be seen here.
Syndra is the third champion to currently have a difficulty rating of 100, the first being Cassiopeia, the second being Orianna, and the fourth being Draven. On release, her difficulty rating was originally 90.
Each of Syndra's abilities gain new graphical details when levelled to max rank. Dark Sphere gains a darker shockwave color (red for Classic skin, orange-gold for Justicar) and cracks the earth; Force of Will gains a similarily-colored, larger shockwave as well as an energy trail following thrown spheres; Scatter the weak gains a similarily-colored energy wave and electrical jolts; when attaining the max rank of Unleashed Power, the three orbs floating around Syndra will have a slight change of appearance and will leave a trail.
Syndra is the second champion speculated to be omnipotent, or nearly so. The first one was Xerath.
However, much like Xerath himself, she is still severely limited
As seen in this video, Syndra appears to be able to use the balls from another Syndra.
The fact that Syndra's ultimate (Ultimate Power) can use up to seven balls is possibly a refference to Dragon Ball as there are seven Dragon Balls.
Syndra's name and appearance shares some similarities with Sindel from the Mortal Kombat franchise.
In addition, it also looks like the "Mantle of Decorum", Ionia's highest decoration. However, it is placed on her forehead instead of floating behind her head, as a sort of symbol of power, much like a crown.
In her earlier designs, she was intended to have a Mantle of Decorum; however, this was most likely removed because it contradicts with established lore: the Mantles of Decorum are reserved only for Ionia's most revered and respected people.
Justicar Syndra is possibly a version of Syndra from an alternate history, where she instead embraced her elders' teaching and became a force for good. This theory is based on her warmer color scheme, use of white feathers and golden spheres. Her helmet also resembles the sun, a symbol of divinity, and her spheres contain images that resemble a "Mantle of Decorum".
The primary play on words is regarding her lore where she was deemed mentally unbalanced by her Ionian elders (as balance is a defining virtue in Ionian culture), and stands upon on her dark spheres to prove that she "has balance."
It also refers to Syndra's champion balance as she was reportedly overpowered during development.