So today I was playing Rampage and I continued to charge a pebbles or magmus. At the end of my charge right before I would hit them, they would stun me even though I had 5+ charges meaning that I would have magic immunity (as you get it when you are 4+ charges). It happened at least twice during this match (most likely more) and most times led to my death and subsequent raging as my teammates called me idiots saying rampage never had magic immunity. However, I checked it up and he does have it when he has more than 4 charges, which I clearly do. http://honwiki.net/wiki/Magic_Immunity
Working as intended. Rampage loses his Magic Immunity on impact (right before stun), so when Magmus stuns right before impact (Rampage actually impact Magmus, when he is during invulnerable state), stun on Rampage is applied (if you look at buff then you will see that it doesn't give you magic immunity anymore)
Rampage's buffs when charging:
Rampage's buffs when impacting enemy (you gain bonus movementspeed and Unitwalking for 3 seconds on impact, but you are no more under Magic Immunity):