dun waste time, straight train overpowered hero. i would say lunox. seems escaped from ban lately.

however, in my opinion, gusion is the best hero to train. just play him until u can win 100% 1vs5 in custom mode. only then go classic. no need to do rank until you reach lvl30. season is still early.

just incase you've spent your gold on useless hero, these are viable cheap hero

tank: mino/akai
mage: cyclop
sin: saber (free)

do not buy hero using gold if you can use ticket to buy.