Spider-Blessed Assassin (Reworked)

Level 3: Assassinate

You are at your deadliest when you get to drop on your enemies. You gain advantage on initiative rolls. In addition, during the first round of combat, you have advantage on attack rolls against any creature that hasn't taken a turn yet. Any hit you score against a creature that is Surprised is a Critical Hit.

You also gain proficiency with the poisoner's kit.

Level 3: Backstab

You know exactly how to exploit an enemy’s distraction or panic. Once per turn, when you hit a creature with an attack that qualifies for your Sneak Attack feature, you can add flat bonus damage to the attack.

• Bonus Damage: Equal to 1+your proficiency bonus.
• Restriction: You cannot apply this bonus damage to an attack that already benefits from your Assassinate feature.

Creator note: you can use this ability in the same turn you used Assassinate by attacking with your off-hand weapon.

Level 3: Surprising Angle

Your body has adapted to dive and strike from unexpected heights. You gain the following benefits:

• Acrobatic Drop: You take no falling damage if the fall distance is 30 feet or less, and you do not land prone after such a fall.
• Death from Above: When you make a melee weapon attack from above (at least 10 feet) as you jump or fall on your target, if you can apply Backstab to the damage, you may apply it twice instead.

Level 3: Defensive Reflex

This ability is an extension to the Uncanny Dodge ability, so it unlocks at lv5.
When you become the target of a successful attack, you may choose one as a reaction:

• Uncanny Dodge: You halve the damage, rounded down
• Retreat to the Shadows: You take the full damage of the attack. You may roll for Stealth. If you succeed, you become hidden. You may only use this option if there is a cover or dark area nearby (5 feet) you can use to hide, but moving there as a part of this action won't trigger Opportunity Attacks. If you became hidden this way, when you use Sneak Attack in your next turn, add an extra 1d6 to the damage. 

Level 9: Form of the Arachnid

The spider-blessing deepens, allowing you to morph your physiology to match your patron.

As a bonus action, you can sprout four chitinous spider legs from your back, or retract them. While these legs are active, you gain the following benefits:

• Hands-Free Climbing: You gain a climbing speed equal to your walking speed. You can move up, down, and across vertical surfaces and upside down along ceilings, while leaving both of your hands completely free to hold weapons, shields, or items.
• Web Weaver: You can cast the Web spell without requiring any components. Your spell save DC for this spell equals 8 + your Proficiency Bonus + your Dexterity modifier. You can cast this spell once for free, and you regain the ability to do so when you finish a long rest. When you cast this spell, if exactly one creature is caught within the spell's area, and that creature fails its saving throw against the spell, you gain temporary hit points equal to your Rogue level.

You can also choose to turn your damage into Poison damage on an attack that applies Sneak Attack. When you turn your damage into Poison damage this way, the target must throw make a successful Constitution saving throw against your DC (8 + your Proficiency Bonus + your Dexterity modifier) or it becomes Poisoned until the end of it's next turn.

Level 13: Fade into Legend

You can vanish after scoring a kill

• Whenever you kill an enemy during your turn, you may roll for Stealth as an extra Bonus Action. If you succeed, you become hidden. You have Advantage on the roll unless an enemy is within 5 feet to you. You may only use this option if there is a cover or dark area nearby you can use to hide.
• Your mastery over your arachnid form reaches its absolute zenith. Manifesting or retracting your four chitinous spider legs is now a Free Action.

Level 17: Apex Execution

Your venom becomes so corrosive that it melts through natural immunities.

Corrosive Toxin (Passive): Your venom behaves like a flesh-melting acid. You ignore Poison Resistance. Whenever you deal Poison damage to a creature that  has Immunity to Poison damage, the target takes Acid damage instead. The damage dealt is equal to half of the original damage, rounded up.

• Permantent death: Enemies that die within 1 minute of taking Poison or Acid damage from you cannot be resurrected with spells that require an intact body. Their bodies also cannot be raised as an undead.
• Apex Execution (First Round of Combat):
  When landing an Assassinate attack in the first round of combat, you deliver a specialized neurotoxin depending on your weapon:
  • Ranged Option: Neurotoxin Dart
    The target of your attack must pass a Constitution saving throw (DC 8 + your Proficiency Bonus + your Dexterity modifier) or become Stunned until the end of its next turn and takes 2d10 Poison damage. On a successful saving throw, it takes half damage instead and doesn't becomes Stunned.
  • Melee Option: Poison Overload
    Adds 2d6 Piercing damage to the attack, as your spider legs impale your target. The target must pass a Constitution saving throw (DC 8 + your Proficiency Bonus + your Dexterity modifier) or becomes Paralyzed until the end of its next turn. If that creature dies before the end of your next turn, it detonates, forcing all creatures within a 10-foot radius to pass a Dexterity saving throw (8+ your Proficiency bonus+ your Dexterity modifier) or take 6d6 Poison damage (half on a success). You are completely immune to this effect.

Creato note: Yes, the assassinate crit doubles the damage from this ability (except the detonate damage).