Freljord wide "Frost" Mechanic

Would it be possible to change Braum, Ashe, Lissandra, and Trundle to all work with the "Frost" debuff that Sejuani has? Just some quick ideas:

Ashe: Has increased crit damage against enemies affected by "Frost". 5 /10/15% at levels 6/11/16. Q applies Frost and slows enemies as long as Frost is active. Lissandra: Abilities refund a portion of the cost when hitting an enemy afflicted by Frost. All of her abilities now apply frost. Braum: Enemies afflicted by "Frost" will receive a stack of Winter's Bite as long as they are afflicted by Frost. Braum's Ult now applies Frost. Trundle: Pillar: Enemies in range of the pillar have frost applied to them and are slowed for 10%. Domain: Trundle no longer gets movement speed. Rather enemies inside the domain double the percentage of slow from a source of Frost.

Just some ideas I had, but I think it would be cool to have mechanics that were shared by other champions. Similar to how Singed could help Cassiopeia with poison. Don't know if there are similar ways to do this for other themed champions (ie: Ninja's, Shurima, Darius/Draven, Piltover). Might be fun since the lore is being revamped.