Whirlwind was a Skylander influenced by starships from Star Control 2; his Tempest Cloud ability works very much like the spinning blade discs of the game's Kohr-Ah Marauder ships.
Originally, his main attack was a Wind Projectile attempt, but after many iterations, the Wind Project was deemed visually weak.
After several meetings, a designer jokingly said "what if she shot rainbows" to which Paul Reiche enthusiastically replied "Yes! Make it the deadliest rainbows ever." Whirlwind would continue to really set the bar high for Skylander's insane abilities.
The Rainbow theme really let its upgrades shine, with the Rainbow Singularity being a benchmark for over-the-top powers.
The slow, methodical approach of its seemingly harmless projectile conveys a sense of disarming calm before it explodes into rainbow death.
The Dual Rainbow upgrade was supposed to be named Double Rainbow after the Yosemitebear Mountain meme, but was changed due to a legal issue (there is an ice cream company by that name)
