Actually, most of the mechanics needs rework:

A ranger and gear's rarity must be redefined. Higher rarity means he/she has something that lower rarity completely lacks (other than sell value).

A ranger's type must be reinforced and limited. A strength/intelligence ranger's movement, attack speed, and critical rate should not exceed a certain hard value even with gears. An agility/intelligence ranger's defence should not exceed a certain hard value even with gears. A strength/agility ranger's normal and skill splash damage should not exceed a certain hard value even with gears.

A ranger's attack range should not exceed a certain hard value. That says, Junko and Kid must be nerfed.

A ranger's maximum kill for one attack should not exceed a certain hard number. To kill more, use attack speed.

Towers and guardians should have invincibility period in the beginning.

An offensive PvP team should be able to choose enemies' tier: lower, equal, or higher, and either rewarded or imposed penalties accordingly.

A defending PvP team should have benefits of being a lower tier or disadvantage of being a higher tier.

A gacha should be a step gacha instead of pure gacha, and a player with great resilience yet terrible luck should be rewarded, while a lucky player should not.