Thread:AnataBakka/@comment-34722333-20200214033538

If an ally is targeted by an allied on top of them, they don't become  by any means. It's just not a possible interaction. It's not a displacement either. It will be treated as collision, similar to how works. If is present in the wall after the duration of the ability ends, he will move closest outside of it. only considers enemies that are airborne as in the effect. Allies don't have that indicator on top of their heads (in-game) to signify they are "AIRBORNE" when they're hit by ally terrain, therefore can’t cast the ability.

I came across this rather comical video glorifying the fact that Trundle’s pillar can interrupt allied channels. I think it will help.

I suggest you watch it. 