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Alchemist

Broken Glass - Resets the cooldown on Concoct
Potion - You can't get bad effects from Potions
Crystal Meth - You can easily get drinks as you can brew them
Grenade - Holy Hand Grenade
Bow and Arrows - Poison / Flaming

Assassin

Hammer - Assassinate
Sword - Assassinate
Lightsaber - Assassinate

Barbarian

Hammer - Leap
Sword - Leap
Lightsaber - Leap
Space Capacitor - Roar
Space Fluctuator - Roar

Illusionist

Hammer - Grand Disappearance
Sword - Grand Disappearance
Lightsaber - Grand Disappearance
TNT - Grand Disappearance
Glue Mine - Grand Disappearance
Grenades - Grand Disappearance

Lawyer

Gun - Useful for duels, either you get 10 of their rupees or you win and they die. Win-win. Even better, try to get life insurance and then do this.
Not an item, but Russian Roulette is useful for the same purpose.

Merchant

Light Wand: Cards of Fate - SHOPS
Wild Card - SHOPS

Necromancer

TNT - Gets you soul power
Phaser - Gets you soul power
Tome of Magic - Gets you soul power
Gun - Gets you soul power
Grenades - Gets you soul power

Paladin

Lasso - Sets up Holy Hammer
Space Capacitor - Sets up Holy Hammer
Space Fluctuator - Sets up Holy Hammer
Tractor Beam Generator - Sets up Holy Hammer
Banana - +2 spaces, good for Holy Hammer, also can be combined with Condom for +10, anything with set spaces is good for Holy Hammer setup
Pogo Stick - Sets up Holy Hammer


Priest


Light Wand: Revive - For when your Resurrect is on cooldown.
Anhk of Resurrection - To ensure you can always resurrect your teammate.

Saboteur

None of note, this class kinda sucks anyways

Sorcerer

Light Wand: Cards of Fate - Get a Bomb, cast Pyroblast and then throw bomb at them
Time-travel Condom - Sorcerer can steal a banana from Tarzan in the Pawn shop, then use this to go forward 10

Succubus

Hammer - Seduction
Sword - Seduction
Lightsaber - Seduction
Teleporter - Seduction
Explosive Sheep - - Seduction, place Sheep, roll, blow sheep.
I'm pretty sure more explanation would make this topic more interesting. You assume a great deal of knowledge here. Some players will be rather new and could do with some tips from an expert like you.
Great list Looby You should move this post to tips section of the forum. I'm just going to add a few supplemental items but I say you pretty much covered it:

Alchemist
Bows and arrows
Lemon/Gun

Can you expand upon crystal meth? I'm not too familiar with it.


Assassin
Teleporter
Cake
Tractor Beam/Lasso


Barbarian

Teleporter
TNT
Magic star (incap'ing multiple times and shield for defense)
Sheep (set it, then leap or leap to someone's space, set it, roll, then explode it)
Hookshot (might be a stretch, but because of its 12 range vs barbs 10, use it then leap to opponent's space/roll for roar back)

Illusionist
TNT
Glue mine
HHG

move back, set it, then use

Merchant
Holy water/grenade- one or the other
Teleporter for fair trade (for team games)
Any crystal
Balaclava+gun (Gun to use against opponents with teleporter, they set it then fair trade...Actually happens more often than you think)
Helmet/Balaclava/singular breakfast items/Cocaine/sword/diss card:speed exchange that fetch a lot in pawn shop

Necromancer
Magic star
Cocaine
Rocket/Used tome

Paladin
Cocaine

Priest
Rocket/Used tome


Saboteur
TNT (place then delay)

Sorcerer
Gun/Teleporter (see merch)

Succubus
I suck at this class
Ok fine...sheep (seduce, place sheep, roll, then explode it)
RakuDaSwoleya explanation (even brief) would help people like me

also refer to http://www.boardgame-online.com/forum/viewtopic.php?f=31&t=1063

i noticed no class here has banana put down?

Banana is a great item overall but more event based, like you mentioned, rather than class based. I guess it would be good for classes like assassin, barb, paladin or succubus (except when used against succubus in removing STDs) to get a little within their range of attack, and not so much for something like saboteur, necro, lawyer, or priest.
Suppandigirl
RakuDaSwoleya explanation (even brief) would help people like me

also refer to http://www.boardgame-online.com/forum/viewtopic.php?f=31&t=1063

i noticed no class here has banana put down?

Banana is a great item overall but more event based, like you mentioned, rather than class based. I guess it would be good for classes like assassin, barb, paladin or succubus (except when used against succubus in removing STDs) to get a little within their range of attack, and not so much for something like saboteur, necro, lawyer, or priest.

Banana is a great item for Paladin. I'll add it to the list. Anything that can provide reliable spaces (2) is good.