Optimizing an Executioner for Lair Assualt: Spiderkiller

Question

For an upcoming Lair Assault I am building an Assassin(Executioner). I tried to focus on upping damage and maximizing the utility of my poison attacks as much as possible with some lip service to stealth. I'm still fairly new to the game and usually rely on the WOTC handbooks, but there isn't a suitable one for Assassin(Executioner).

Item-wise I have a level 8 dagger which should be good to go but I can take another item at level 9 and one at 10. I have no idea what kind of leather armor would be appropriate and I also have around 3400gp to spend on other gear and consumables. Below is my build so far.

I'd appreciate any suggestions (feats, gear, tactics) as I've never played an Assassin(Executioner) before.

====== Created Using Wizards of the Coast D&D Character Builder ======
Riddick, level 9
Human, Assassin (Executioner)
Executioner Option: Attack Finesse (Executioner)
Assassin Guild Technique: Red Scales
Binding Initiate Option: Binding Initiate (Gloom Pact)
Human Power Selection Option: Heroic Effort
Barovian Escapee (+2 to Stealth)
Theme: Mercenary

FINAL ABILITY SCORES
STR 12, CON 10, DEX 22, INT 10, WIS 10, CHA 14

STARTING ABILITY SCORES
STR 12, CON 10, DEX 18, INT 10, WIS 10, CHA 12


AC: 20 Fort: 17 Ref: 21 Will: 18
HP: 62 Surges: 7 Surge Value: 15

TRAINED SKILLS
Acrobatics +15, Bluff +11, Intimidate +13, Perception +9, Stealth +17, Streetwise +13, Thievery +15

UNTRAINED SKILLS
Arcana +4, Athletics +5, Diplomacy +6, Dungeoneering +4, Endurance +4, Heal +4, History +4, Insight +4, Nature +4, Religion +4

POWERS
Basic Attack: Melee Basic Attack
Basic Attack: Ranged Basic Attack
Mercenary Attack: Takedown Strike
Human Racial Power: Heroic Effort
Assassin Attack: Assassin's Strike
Assassin Attack: Garrote Strangle
Assassin Attack: Poisoned Dagger
Assassin Attack: Quick Lunge
Assassin Attack: Hidden Stab
Warlock Utility: Shadow Warp
Warlock Attack 1: Echoing Dirge
Assassin Utility 2: Cloak of Shades
Assassin Utility 6: Vanish

FEATS
Level 1: Light Blade Expertise
Level 1: Two-Weapon Defense
Level 1: Blindfighting Warrior
Level 2: Venom Hand Killer
Level 4: Venom Hand Master
Level 6: Binding Initiate
Level 8: Cursed Shadow

ITEMS
Bloodroot Poison
Carrion Crawler Brain Juice
Adventurer's Kit
Rapier
Spiked gauntlet
Garrote
Nitharit Poison
Id Moss Powder
Cunning Dagger +2 x1
====== End ======

Answer 1

I am skeptical about the idea that I think you're about to use. Granted, I've only done 1 lair assault and they usually consist of one gigantic encounter split into multiple encounters, but no short rest involved. If I'm thinking what you're doing is correct, you're gonna try to guarantee that when you hit with Cunning Dagger combined with Poisoned Dagger, you'll essentially make a -6 penalty for the first saving throw they would have to make on a Nitharit Poison to try and go for the 2 extra, then 5 extra.

For some reason, My mind is thinking somewhere this is not going to turn out the way you'd think and I don't know why yet. Perhaps its because since the build relies on many different weapons, my mind sees the no magic Ki-Focus yet as a huge disadvantage since you lose 2 attack and damage possibilities for anything else. Since you are a striker and my experience with a Lair Assault as a striker last time: Damage as much as possible as reliable as possible.

Also, for the mention, You might want to look for something that can heal you without too much reliance on the leader (I'll assume you'll have 1 leader max for the Lair Assault).

I hope this at least guides you to what you're looking for.