After researching and many trial and error
This is my conclusion =>
It must be very frustrating that after grinding the game a lot what you get from event contracts are the hero bp that you don't want, but not any more.
After opening many AD crates and collecting many tournament rewards I realised a pattern like for example I got wasp bp once then next getting wolverine is 50% but if i get wasp bp again means 2 in a row then getting wolverine bp has a higher chance than wasp bp
generally speaking, you can get up to 3 in a row the same hero and only once I got mole bp 4 in a row which is very rare to occur
IN CONCLUSION =>
IF YOU like want salamander or pision bp then before collecting the event contract make sure that you got mole or seraphim bp 2 or 3 times in a row from crates or tournament rewards
This trick also works on common heroes as well
DISCLAIMER :
This trick might not be accurate so attempt it at your own risk
well there is is nothing to lose though right?




