I am working a a Subclass for the Range and i would like feedback, it isn't finished but i want to get everything right before making the 15th level ability 

Elemental Infusions

At 3rd level, you chose the one Elemental Infusions and another at 7th level:

You can only use one Infusion per turn

Acid Infusion

When you hit with a Ranged weapon attack you can deal and Extra 1d6 Acid Damage and the targeted creature for the next minute AC is reduced by 1. (This abilitiy can't be stacked on one creature)

The ability gains an additional 1d6 base damage and use at 7th level,11th level, and 15th level

Cold Infusion

When you hit with a Ranged Weapon Attack, you can deal an Extra 1d6 Cold Damage, the targeted creatures speed is reduced by 15ft until the end of your next turn

At 3rd level this ability has 3 uses, This ability gains an additional use at 7th level,11th level, and 15th level

Fire Infusion

When you hit with a Ranged weapon attack you can deal and Extra 1d6 Fire Damage and the targeted creature for the next minute takes 1d6 Fire Damage at the begging of its turn, unless it uses its action to put out the fire.

The ability gains an additional 1d6 base damage and use at 7th level,11th level, and 15th level

Lightning Infusion

When you hit with a Ranged Weapon Attack, you can deal an Extra 1d6 Lightning Damage, the targeted creature can't take Reaction until the end of your next turn

At 3rd level this ability has 3 uses, This ability gains an additional use at 7th level,11th level, and 15th level

Elemental Fusion

At the beginning of 7th level, You gain the ability to do two Elemental Infusion instead of one per turn

Elemental Infusion Mastery

Starting at 11th level, You chose one Elemental Infusion Mastery and another at 15th level: 

Necrotic​ Mastery Infusion

When you hit with a Ranged Weapon attack, you can deal an extra 2d8 Necrotic Damage and are healed that mach damage 

You can use this Ability 4 times, you gain 2 more uses at 15th level. This ability recharges after a long rest 

Poison Mastery Infusion

When you hit with a Ranged Weapon attack, you can deal an extra 2d8 Poison Damage and makes a CON saving throw DC 18 or become Poisoned until the end of your next turn. 

You can use this Ability 4 times, you gain 2 more uses at 15th level. This ability recharges after a long rest 

Radiant Infusion Mastery

When you hit with a Ranged Weapon attack, you can deal an extra 4d8 Radiant Damage and Attacks make against it has advantage for one minute, the creature also glows with Dim Light for 10 ft, When the creature is hit with an attack, it can make a CON saving throw DC 10, on a fail, the creature no longer glows and attacks made against it no longer have advantage

You can use this Ability 2 times, you gain 2 more uses at 15th level. This ability recharges after a long rest 

Thunder​ Mastery Infusion

When you hit with a Ranged Weapon attack, you can deal an extra 4d8 Thunder Damage and makes a CON saving throw DC 18 or be Deafened for one minute. While the creature is Deafened, it takes 1d8 [Tooltip Not Found] at the beginning of its turn, at the end of the creatures turn it can reroll the saving throw, on a success the creature is no longer Deafened.

You can use this Ability 2 times, you gain 2 more uses at 15th level. This ability recharges after a long rest 

I'll come back later for a more in depth review... but here's a few things I can say right now;

1. Make the infusion DC equal to your spellcasting DC
2. the thunder mastery needs a tooltip fix
3. no subclass spells known list?
4. Can you give us some flavor text so we can understand what you're trying to make... Like atm I'm seeing this like an arcane archer or elementalist ranger subclass

thanks i have fixed the tool tip, i can make it the spell save DC, and no Spell list because this is more focused on Ranged weapon attacks, i could add a cantrip to the infusion