Bomb Effects
Caltrop – Caltrop Bomb (Tactical) – Slows and stuns enemies by
covering an area of ground with metal spikes. Perfect for stopping
pursuits and blocking narrow paths. Ezio is not damaged by caltrops.
Lamb’s Blood – Blood Bomb (Tactical) – Sprays blood in an explosion,
causing fear and panic. They incapacitate, but for only a short amount
of time.
Shrapnel – Splinter Bomb (Lethal) – Sprays shards of metal in
all directions, hurting or killing anyone caught in the blast. Like a
modern frag grenade, beware of killing civilians.
Salt of Petra – Smoke Decoy (Diversion) – Releases a thick smoke that draws guards to
it. Useful for luring guards and breaking their line of sight. Less
noisy and more discreet than other diversions.
Phosphorous – Smoke Screen (Tactical) – Blinds victims with a bright flash and creates
smoke that breaks line of sight. Enemies caught in the smoke are easy
to kill, and Ezio can see through the smoke with his eagle vision.
Datura – Datura Bomb (Lethal) – Releases a cloud of poison smoke that
hurts and incapacities anyone caught by it. Beware of killing
civilians, the effect is similar to the Poison Dart.
Coal Dust – Thunder Bomb (Lethal) – Creates a powerful explosion, it is less
powerful than other bombs, but will stun and disable anyone not killed
in the explosion.
Skunk Oil – Stink Bomb (Diversion) – Drenches anyone
with a strong stink caught in the blast, very useful for separating
targets from crowds or other guards. Any guard caught in the stink
will stop until the effect has worn off.
Sulfur – Cherry Bomb (Diversion) – Pops with a loud noise, and attracts guards from far > and wide to investigate the noise.
Pyrite Coins – Gold Bomb (Diversion) –
Like throwing coin on steriods, the explosion will spray an area with
coins, any citizen will become hostile to guards coming to
investigate, creating a big instant crowd and diversion.
Bomb Casings
Fuse Shell – The default casing, it bounces off surfaces or NPCs and
explodes after three seconds. The extra time can be useful for
escaping and hiding before the bomb goes off.
Impact Shell – Explodes on impact with an NPC or surface. If you need an immediate > explosion, use this casing. Best used for lethal bombs, where you’ll rarely need
to set a killer trap, or just need to defeat a large group quickly.
Trip Wire – Explodes when enemies walk near, a perfect casing for
setting traps. Set these on guard patrol routes.
Sticky Pouch – Sticky to any surface of NPC it lands on, then explodes after five seconds.
The delay helps Ezio escape, and being able to land a bomb on a
specific target means you always know at least one of your intended
targets will be caught in the blast.
Bomb Gunpowder
Indian Gunpowder – 2 meter blast radius. Best used for precision
attacks where you need to limit civilian casualties.
Arabic Gunpowder – 3 meter blast radius. Medium, for when you need a slightly larger
effect on your targets.
British Gunpowder – 4 meter blast radius. Best used for large groups, save these large blasts for tactical bombs that limit civilian death.
Best Answer
Here's an overview of what each of the challenges provides you if you complete them. I don't know what is more worthwhile to you so you decide.
Assassins Guild:
Sending your assassins on missions in Mediterranean Defense gives you a free 9% bonus in the odds of success. It could be helpful to you if you want to send your assassins out on missions with the least amount possible with guaranteed survival.
Self explanatory. You can call assassins to help you out more often since the meter will recharge faster. If you need/want the help, this would be a great challenge to meet.
Unlocks Altair's Sword which is a decent sword with stats 5/3/4. It's not a max stat sword this time, but Yusuf's Turkish Kijil is.
Mercenaries Guild:
Reduces the cost of hiring Mercenaries from 150 to 75. Mostly useless, money is easy to come by.
Hired Mercenaries will protect you from any hostile/troublesome civilians. So if you anger people from pickpocketing them, they're dead. If beggars come at you, they'll be pushed away. They'll probably even detract or kill off stalkers you might come by. Not particularly useful if you asked me.
Unlocks the Broadsword which is an strong heavy sword with stats 5/4/4. It's not a max stat heavy weapon though, but the Almogavar Axe is.
Romanies Guild:
Reduces the cost of hiring Romanies from 150 to 75. Mostly useless, money is easy to come by.
When a hired Romani distracts a guard, they will (slow) poison them when you send them to distract or walk by them. Useful if you want to kill guards with the least amount of trouble.
Unlocks the Romani Stiletto which is a decent knife with stats 5/3/4. It's not a max stat knife, but Mehmet's Dagger is.
Thieves Guild:
Reduces the cost of hiring Thieves from 150 to 75. Mostly useless, money is easy to come by.
Enables thief stealing. Thieves you hire will steal from civilians as they pass by them and loot dead guards. A necessity if you want the Fast Fingers achievement.
Unlocks the Ottoman Mace which is an decent mace with stats 4/4/2. Not my kind of weapon but it has a decent speed over all the other faction weapons at the cost of some damage and speed. Mostly useless IMHO.
Bombs:
It just gives you a little more of the ingredients from the chests in the dens. I've always had full ingredients at all times (even when using bombs somewhat frequently) so I don't know how useful this would be.
Allows you to carry an additional bomb per pouch. I don't know how useful this is considering you can replenish your bombs from the weapon wheel.