Cluster Bolt

 is a unit. It produces one-time burst damage for both players, but less for the opponent.

Strategy
is a powerful source of burst damage that can devastate an unprepared opponent, but increases the pressure on oneself as well. It can synergize with convenient Defense sets by making all the defense spent as Prompt. It is best used against an opponent without access to efficient defenders, for example an opponent playing a Tatsu Nullifier rush. If the four damage forces them to buy two Rhinos, then Cluster Bolt is great. It can also be used to deny important purchases - for example, if the opponent has set up to buy a Defense Grid next turn, but buying a Cluster Bolt places them under so much pressure that they can't do so without getting breached.

Notable is that, since has no Gold cost, it can be bought even after a player has lost all their Drones and other Gold-producing units. If bought at times like this, it can potentially turn close games from losses to draws or even victories, although such situations are rare. As such, in games where can be bought it can be very important to destroy enemy Conduits in the lategame.

All-in
The Player 1 rush tends to go: With some variation on when the bolts are fired off. You probably want to pile up some green to launch multiple on the same turn.
 * C
 * CC
 * 1) C Bolt
 * 2) CC Bolt

The best Player 2 counter for this is to grab a single conduit and stock up on Gauss Cannons: Kill the Drones before the Conduits and you shouldn't have much trouble winning: if on any turn you don't have enough gold to build a Gauss Cannon, build a conduit instead.
 * DC
 * G
 * GD

The Player 2 rush is: The s are coming out a bit faster because Player 2 can pick up the Conduits much faster, the Gauss Cannon all-in counter isn't as effective: go Blastforge on turn 2 instead, and run out your opponent's supply of Bolts. You can / should pick up a Conduit before you run out of drones so you can stock up on Green and counter-bolt to take out their Conduits and win (See the linked video below for a more detailed explanation on how to play this matchup).
 * DC
 * CC
 * CC
 * 1) Bolt ...

With Galvani Drone, Player 1 has an advantage. Instead of ramping for a 2nd Bolt, constant attack.
 * 1) C GaGa
 * CC
 * 1) Bolt CC
 * 2) Bolt GE
 * 3) Bolt G

Surviving the Cluster Bolt All-In
A All-In has a very high attack potential and can often catch you unaware. If your opponent buy multiple Conduits, read the set carefully and if there is no others units consuming lots of green like Asteri Cannon you know they are going for. You then have to buy breach resistant units (with high-Health) like Gauss Cannon. As a matter of fact on the turn your opponent decides to use s you will be breached (barring units like Urban Sentry or Plexo Cell), so in order to minimize the damage DO NOT build low-health units like most of the red units.

Openings
Gauss Fabricator lines.

Player 1 Rush:

DD/CC/DD/Gauss Fabricator/BD...

Defend with Walls and Engineers.

Player 1 Econ: DD/DD/DCC/DCC/Gauss Fabricator/GG +Cluster Bolt

All-in attack.

Player 2 Attack:

DD/DDC/DCC/Gauss Fabricator/CCC/2x Cluster Bolt +FDCC

Very all-in attack.

Player 1 Auric Impulse:

11/CC11/CC11/Gauss Fabricator/Cluster Bolt +CF

Trinity Drone adds further efficiency.

Change log

 * April 25th, 2015
 * Gauss Charges constructed decreased from 5 to 4.
 * Gauss Charges constructed for opponent decreased from 2 to 1.