I have tried so hard to get psion but he refuses to come to me. he is the last troop i need from his land dang it.
Me too, opens 20 event keys so far, had no luck 
I opened 8 Vip keys and got a bunch.
What is the chances getting one PSION in a VIP chest?
It’s random and RNG can be a blessing or a curse. For me it seems to average out getting the featured legendary around 20% of the time (no hard data though, just what my impressions have been).
For me it seems it’s about 5% chance. It’s the same % as for gem keys, but if you get a legendary from event keys then it will be the one from the current event kingdom. A nice way to find a legendary troop if you miss just a few of them.