Some ideas on Ivern passive nerf

1. Slightly increase camp channeling time: so that he cannot simply take the camp in situations when there are nearby opponents that want contest it
2. Freeing camps can be interrupted by enemy champions: situations when there is no way to stop Ivern from taking your camp if he managed to apply mark (e.g. https://youtu.be/jIDefNbNn2Q?t=15m7s) This one somewhat overlaps with first suggestion. I personally prefer this one.
3. Give shared buff only if Ivern frees camp, don't give it if he smites it: this will be more fair to regular junglers where they need to spend time and tank buff for the laner to finish it

I do understand that comparing Ivern to other junglers is incorrect due to every champion having unique kit. I am also not an Ivern player or wasn't abused by Iverns. These suggestions come from analyzing MSI games where Ivern dominates jungle in cheesy way.