The 'tier'

hello, i just played this game and the game is so exciting. but still the game doesnt give me the best tutorial.

All i know about tier is just when we upgrade the equipment (eg: weapon) the attack power increases as the tier number.

And if I want to buy equipment with souls, I think it's better to wait until tier 10 (maybe). but I don't know what to do to increase the tier in the shop.

My question is what must i do so the tier in the shop keep increasing??

 

btw, the like & share event is so great. My coin now is about 300k.

Equipment Tier - Equipment Tiers are determined by character's level. - Level 1 to 4: Tier 1 - Level 5 to 9: Tier 2 - Level 10 to 14: Tier 3 - Level 15 to 19: Tier 4 - Level 20 to 24: Tier 5 - Level 25 to 29: Tier 6 - Level 30 to 34: Tier 7 - Level 35 to 39: Tier 8 - Level 40 to 44: Tier 9 - Level 45 to 49: Tier 10 - Level 50 to 54: Tier 11 - Level 55 to 59: Tier 12 - Level 60 to 64: Tier 13 - Level 65 to 69: Tier 14 - Level 70 and higher: Tier 15

Equipment Tier - Equipment Tiers are determined by character's level. - Level 1 to 4: Tier 1 - Level 5 to 9: Tier 2 - Level 10 to 14: Tier 3 - Level 15 to 19: Tier 4 - Level 20 to 24: Tier 5 - Level 25 to 29: Tier 6 - Level 30 to 34: Tier 7 - Level 35 to 39: Tier 8 - Level 40 to 44: Tier 9 - Level 45 to 49: Tier 10 - Level 50 to 54: Tier 11 - Level 55 to 59: Tier 12 - Level 60 to 64: Tier 13 - Level 65 to 69: Tier 14 - Level 70 and higher: Tier 15