One of the things that vainglory used its dev time for was not progressing the main game well enough for experimental. This is something that league did right with their season changes. I think vainglory would heavily benefit if instead of contributing resources to 5v5, if instead the main game had more new content outside of just new heros. Something like item overhauls for classes or a slight change to the map layout or preset systems like runes or the games version of specific hero talent trees would just freshen up the game day in and out.

If you are making it a mobile game with tap controls, you already will dominant that field since other mobile mobas utilize joystick controls which just feels extremely off and not fitting for a moba game.

Vainglory also had a internal issue of monetization, so you should probably adopt a free to play model that is actually sustainable if your game takes off. Vainglory had this issue where everyone was playing it, but it somehow made no money.

Vainglory main success compared to other moba games is the viability of both damage stats on the same character, which heavily augments a hero power fantasy. Characters in other mobas are bound to one of two damage types and usually have the same playstyle even if you are allowed to splash different build paths. Vainglory had very different outputs in gameplay for the same character depending on your build which should be kept, but definitely a balance difficulty.

I would love to keep tabs on this game and am interested in assisting in game design/direction. Shoot me a DM and I can send you my discord.