Represented by Vaseline, jam, mustard, toothpaste or similar gooey substances, or by powder such as talc. This will kill immediately after contact with the skin even if it is wiped off. This sort of contact poison is deemed to be no longer effective if it has dried enough that the victim does not notice it (be honest, please). Gloves or anything else which prevents the poison from coming into contact with the skin will protect you.
As contact poison is dangerous to anyone else who might touch the surface in question, anyone using it in a public area will be put on the wanted list. This includes a target's door handle. That's worth repeating; contact poisoning a target's doorhandle will make you wanted. Ask the Umpire for further clarification. The umpire will take a dim view of anyone felt to be overusing contact poison, even if they are already on the wanted list.
Paper planes with contact poison on the tip may be used as poisoned darts if they are appropriately labelled. Please be careful with these, as they can quite easily cause injury at close range.
Please take care not to use any substance likely to cause allergic reactions as a contact poison - the umpire will inform you if any of your targets have such allergies, but err on the side of caution in all cases.
Strongly-flavoured substances added to a victim's food or drink count as poison and will kill the victim as soon as they notice the taste. If the poison is dilute enough not to be tasted it will not work. Note that experiments to establish the required dose may well end up killing the guinea pig. Be careful not to use as poison any substances which may cause allergic reactions, especially almond essence.
Food which normally tastes strong or spicy does not count as poison on its own. Buying your victim a Pizza Gamberi from Pizza Express does not count as a poisoning, nor does leaving an extra-strong Phileas Fogg tortilla chip in their pigeon hole.
Cards, letters and parcels may contain contact poison or detonators. Musical birthday cards are a particularly useful type of premade letterbomb as they already come with a detonator. Poisoned letters should usually be signed, eg. A. Sassin and must always have a disclaimer reading something like:
This is a letter for the mock assassination game run by the Cambridge University Assassins' Guild. The substance contained within is [insert name of substance] and is completely harmless. Queries should be addressed to this term's Umpire, Martin O'Leary of St John's College (assassins@srcf.ucam.org).
Anyone failing to replace the text `[insert name of substance here]' with the actual name of the substance in question will be made wanted for extreme stupidity.
Powdered contact poison (talc, flour, etc.) must not be sent through the Royal Mail. Cards, letters, parcels, etc. that are sent through the mail service (University or Royal) or are handed to porters, and have leaked their contact poison, are deemed to have killed innocent victims. Remember: Careless Talc Costs Lives.
`Blackmail' letters must be individually approved by the umpire before use. These are poisoned letters which offer a poisoned victim the chance of an antidote in return for promptly killing a player chosen by the sender. The receiver will be made wanted if the killing breaches normal targetting rules, but at least he won't be dead ... perhaps a legal method of killing could be contrived. Note also that an inappropriate choice of target by the sender (e.g. a non-player) may end up making the sender wanted too.
Fake explosive devices may be constructed in order to blow up other players. It should go without saying that attempting to actually blow up other players with real bombs is strictly prohibited.
All bombs should be clearly marked with the words ``FAKE BOMB" (the word FAKE must not be smaller than the word BOMB) and a disclaimer to the effect of:
This is a harmless imitation bomb constructed for the purposes of a game played by the Cambridge University Assassins' Guild. Please do not touch. Any queries should be addressed to the Umpire, Martin O'Leary of St John's College (assassins@srcf.ucam.org).
The disclaimer should be on the outside of the bomb, visible as soon as the bomb is seen. If you know what a real bomb looks like, ensure that your imitation bomb does not look like one. In particular, avoid leaving electrical wiring poking out of the bomb.
The basic component of any bomb is the detonator. This can be anything which, when triggered, emits some sort of loud noise as a signal that the bomb has gone off. Cap detonators, party poppers, balloon-and-pin arrangements and battery-powered buzzers are all suitable for use as detonators.
A detonator which goes off will kill anyone touching it, and may therefore be sufficient as a letterbomb or pigeonhole bomb. Most bomb-makers, however, will also want to include additional explosives, so that the target can be killed when not touching the detonator. Many substances may be used as explosive; good examples are water, plasticine, styrofoam packing chips or cotton wool, all held in a closed container such as a bottle or a box. Air only counts as an explosive if contained in balloons. If you are not sure whether something can be used as explosive, ask the Umpire.
It is not permissible to merely label something found at the scene as a bomb; all components must be brought by the bomb-maker. Thus, merely writing ``FAKE BOMB" on someone's bin is not allowable.
Explosives must be attached to the detonator either directly or, for example, with a piece of string. When the detonator is triggered, all explosives attached to it will explode. It is worth noting that if you can separate the detonator from the explosive without triggering the bomb, the explosive will become harmless (the detonator can still kill you, however).
Explosives must, in addition to the disclaimer, be marked with the volume
of explosive they contain and the corresponding blast radius. The blast radius
should be clearly displayed to someone seeing the bomb. The blast radius (in metres) is
determined by the formula
, where 
is the volume of explosive in litres. The radii for some common volumes of explosive are given here:
| Volume in litres | Radius in metres | Volume in litres | Radius in metres |
| 0.5 | 0.6 | 5.5 | 6.8 |
| 1.0 | 2.4 | 6.0 | 7.1 |
| 1.5 | 3.5 | 7.0 | 7.5 |
| 2.0 | 4.2 | 8.0 | 7.8 |
| 2.5 | 4.8 | 10.0 | 8.1 |
| 3.0 | 5.3 | 12.0 | 8.9 |
| 3.5 | 5.7 | 14.0 | 9.3 |
| 4.0 | 6.0 | 16.0 | 9.6 |
| 4.5 | 6.3 | 18.0 | 9.9 |
| 5.0 | 6.6 | 20.0 | 10.2 |
When an explosive goes off, anyone within its blast radius (as measured from the centre of the explosive, should anyone use an explosive large enough that this is an issue) will be killed. However, objects between you and the explosive will decrease the effective blast radius:
It is possible for a sufficiently small explosive to have a blast radius of zero or less, but any explosive will still kill you if you are touching it when it goes off.
In general, bombs can only be triggered by some action of the victim; you may not detonate your own bombs by remote control, timer or any kind of ``dead man's trigger", and you may not arrange that the bomb will be set off by neighbours or bedders. You may, however, still be killed by bombs set off by the incompetence of your companions or yourself. Bombs with timers that delay detonation for a short while after the victim triggers the bomb are allowed, if you manage to make one. Additionally, any kind of trigger may be used if the bomb is wholly within the target's room, because any assassin foolish enough to give you the opportunity to plant bombs in their room deserves it. If any of this is not clear, ask the Umpire to explain.
Bombs planted on a target's door which go off when the door is unlocked or the doorhandle is turned are not allowed as there is no reasonable defence against them.
Bombs may be dealt with either by disarming them, or by detonating them from a safe place outside the blast radius. Bombs cannot be destroyed by other bombs. For people with smaller rooms worried about being able to get out of the blast radius of a large bomb, you may contact the umpire concerning the buiding of a bomb shelter/barricade/bunker in your room.
Whenever you construct, disarm or detonate a bomb, please describe the bomb's construction as fully as possible in the report you send to the Umpire. In addition, if you have any components of a detonated bomb (particularly electronics), please keep hold of them and the Umpire will arrange that they are returned to the original owner. None of the explosives or detonators used in a bomb which has gone off may be re-used within the same game by any player, but if you are able to disarm the bomb without setting it off you may keep it and attempt to use it yourself as long as it is returned to the owner at the end of the game.
You will find it difficult to do so because of the volume of explosive required, but building a bomb to destroy, for example, an entire college is in any case not permitted. (Attempting to do so will probably make you wanted anyway.)
It is suggested that any players wanting to construct particularly clever or unusual bombs check with the Umpire before doing so to be sure that their invention is legal.