Do not waste your hard-earned Gold. Understanding the algorithmic stat rolling system is the difference between being hard-stuck in World 6 and dominating the PvP Arena.
Every hero in Summon Heroes comes with randomized intrinsic stat modifiers. You can spend Gold in the Main Hub to reroll these stats algorithmically. Stats are graded on an alphabetical tier list from 'D' (worst) to 'S' (excellent), capping out at the ultra-rare 'X' (perfect) tier.
If you take away one piece of expert advice from this wiki, make it this: Defensive stats are mathematically irrelevant in Summon Heroes.
A common mistake novice players make is rolling for 'X' tier Health or Armor on their frontline tanks. The current endgame meta is entirely dictated by the action economy. The absolute perfect roll for ANY character—whether DPS, Support, or Tank—is 'X' Tier Speed combined with 'X' Tier Cooldown Reduction (CD).