Rogueish Archetype

The Mage Slayer

Some Rogues train to slip past front line forces and disable enemy support. Vanguard scouts, infiltration teams and flanking squadrons might include individuals trained in this manner, though some turn their talents to bounty hunting or kidnapping. They study the habits of spellcasters, learning to recognize subtle signs of incantation and enchantment.

Bonus Proficiencies

When you choose this archetype at 3rd level, you gain proficiency in the Arcana skill.

Silencing Strike

Starting at 3rd level, when you successfully hit a creature with a melee attack, you can force the creature to make a Constitution saving throw. On a failed save, the creature is unable to speak and cannot cast spells with a verbal component. These effects lasts until the end of its next turn.

You can use this feature a number of times equal to your Intelligence modifier. You regain all expended uses after a long rest.

Silencing Strike save DC = 8 + your proficiency bonus +

your Intelligence modifier

Matter over Mind

Starting at 9th level, your keen mind and trained senses allow you to defeat illusions and enchantments.

You can use a bonus action to make an Intelligence (Investigation) check to recognize an illusion, and you can’t be charmed while you are conscious.

Nullification

At 13th level, you learn to negate magic and magical effects. You can cast once each, counterspell and dispel magic. Intelligence is your spellcasting stat for these spells.

Once you do so, you can’t do so again until you finish a short or long rest.

Spell Breaker:

When you reach 17th level, you have fought enough magic users to predict and attempt to disable them before they can attack.

When a hostile creature within 30ft of you begins to cast a spell, you can immediately take an extra turn, interrupting the current turn. If you do, your action for that turn must target that creature or include it in its area of effect. After that turn is complete, the creature continues with the spell's casting.

After you use this feature, you can't move or take actions until the end of your next turn, and you cannot use it again until you finish a long rest.