Rogue: Titian Slayer Archetype

Some rouges are cowards, assassins' or thieves who and slink about in the shadows afraid of what the light may bring. Titian slayers are built different, for only a brave and possibly reckless fool would have the gall to fight the massive Titians of Albion. These hero's stand on the shoulders of giants, ever since the first titian slayer Jack climbed the beanstalk and slew the cloud giant, showing man what could be done when one put fear aside and let their blade do the worrying for them.   Underfoot combat: Starting at 3rd level, you develop a strategy for taking on bigger foes. While you are adjacent to a creature that is two or more size categories larger than you, you can use your bonus action to enter that creatures space. You remain in this creatures space until it moves, or until you use another bonus action to move back to a unoccupied space adjacent to the creature. While you are in a hostile creatures space, you can use sneak attack against that creature if you don't have disadvantage on the attack role, even if you don't have advantage on the attack role. Additionally, while in this space, you have half cover if the creature is two size categories larger than you, and three-quarters cover if the creature is three or more size categories larger than you.

Friendly reminder sizes are categorized in ascending order as follow; tiny, small, medium, large, huge and gargantuan

Knee striker: at 3rd level, you learn the week points in all massive foes, you know how to bring them to their knees. When you make a sneak attack on a creature that is of a size larger than yours, you can forego half your sneak attack dice (rounded down, to a minimum of 1) to knock that creature prone.

Confound the big folk: At 9th level, you are a expert in the art of baffling the big folk, who are slow and unobservant by your standards. You have advantage on dexterity (stealth) checks made to hide from and sneak around creatures that are larger size category than you. Additionally, if you make a check to avoid, climb, or confuse a creature that is one size category larger than you, and the check doesn't already use your proficiency bonus, you can add half of your proficiency bonus to that check.

Fear no monster: By 13th level, your constant experience fighting larger opponents makes you numb to the danger they bring, to others it seems that you are fearless in the face of impossible odds. You can't be frightened. Additionally, when ever you roll initiative, you have advantage on ability checks and saving throws you make until the end of your next turn.

Fell the giant: At 17th level, you knowledge of the massive enemies weak points and how to exploit them becomes paramount for your survival, a toppled titian is a dead titian. Now your weapon attacks against creatures that are at least one size category larger than you score a critical hit on a roll of 19 or 20. Your critical hits also knock the target creature prone.