In the early stages, Permanent Upgrades are a good investment - especially as you only need coins for the upgrade itself once you unlock them by farming XP (which you need to do to be able to level up your Hero)
But as the game progresses, the returns diminish (partly because they are flat increases at best, so the percentage improvement over what you already have is small, and partly because the cost goes up), so especially if you are tight for coins you may want to invest on some other upgrade (especially because for every other thing you spend coins on, you know precisely what you will be getting in return)
This is how the different upgrades play out:
Nimble Hands
Your Attack Speed increases as follows
- Level 1: +2%
- Level 2-13: +0.5% per level
- Level 14-25: +0.25% per level (max +11% at Level 25)
Good Shot
Your Hero Attack increases as follows
- Level 1: +40
- Level 2-25: +15 per level (max +400 at Level 25)
Gun Mastery
This gives a bonus on your Weapon Attack as follows (benefit will be shown in your Loadout Attack)
- Level 1-25: +1% per level (max +25% at Level 25)
Armor Mastery
This gives a bonus on your Armor’s Health stat; benefit will be shown in your Loadout screen, where Health = Hero’s Health (basic from level, plus Max Health upgrade and any bonuses) + Armour Health * Armor Mastery
- Level 1-25: +1% per level (max +25% at Level 25)
Gear Mastery
The damage from your gear (details) increases as follows
- Level 1-25: +1% per level (max +25% at Level 25)
Max Health
Your hero’s Health increases as follows
- Level 1: +100
- Level 2-25: +50 per level (max +1,300 at Level 25)
Melee Resistance and Ranged Resistance
This is your first line of defense against damage (see Defense: Resistance, Armour, Perks for more details), although it’s rather insignificant in higher floors of the Castle / Endless Tower
- Level 1: +40
- Level 2-25: +15 per level (max +400 at Level 25)
Regen Mastery
This is how much you heal when you level up (this can be improved by “Healing” bonuses - e.g. hero-specific or all-hero bonuses - as well as Combat Medic perk)
- Level 1: +100
- Level 2-25: +50 per level (max +1,300 at Level 25)
First Aid
This is how much you heal from health kits - the little hearts that fly to you and increase your health. There’s always one present before the Boss Room in Worlds, Daily Events (not Weekend), and Endless Towers/events, (but not in Castles), and drop when defeating bosses and randomly from other enemies as well (there’s a Skill for some heroes that increases the chances of this)
- Level 1: +50
- Level 2-25: +25 per level (max +650 at Level 25)
Bean Counter
This is a bonus on coin drops - this directly impacts coins dropping from monsters and doesn’t show in the bonus on the end screen (the numbers there are 50% for your last world / Endless Tower and upto 40% on the Battle Pass)
- Level 1-25: +2% per level (max +50% at Level 25)