"These new siege tanks work just like the old ones. When you put 'em in siege mode they get increased range and firepower. They can't move in siege mode, so if you need to reposition 'em, just switch 'em back into tank mode."
The siege tank continues to function as it did in previous games with the dual tank and artillery modes, except it doesn't require as much support as is needed in the original StarCraft. While in "siege mode", the tank cannot fire at "point-blank" range; this "dead zone" leaves the tank vulnerable to attacks by melee units. It is also highly vulnerable to air units. The siege tank bobs slightly when it stops moving.
Siege tanks are strong against marines and hydralisks, and weak against thors, immortals, and zerglings. Given its firepower, siege tanks are also popular with marines and marauders, providing artillery support for both defensive and offensive roles. When combined with the MMM combo, it is especially effective against roaches, stalkers and even deterring colossi to an extent.
Groups of siege tanks do not "overfire". If one zergling attacks twelve tanks, only one tank fires because only one shell is needed for the kill. This means that enemies can no longer take advantage of the tank's slow shot cooldown, further increasing its power and versatility.
Splitting tanks in multiple groups prevents a tank column from entering siege mode all at once and out of position. Other units should screen tanks in siege mode; this prevents tanks from being hit from friendly shock cannon fire when enemy units close the minimum range. The tank's siege mode range is greater than its sight range; supporting a tank with spotters is useful.
Building an army of both siege tanks and thors is possible, but expensive. The combination is difficult to stop.
Siege tanks do not operate well in conjunction with widow mines, as the damage they can do to enemy units (killing them) prevents widow mines from detonating.
Siege tank shock cannons deal 75% less splash damage to friendly units.
LarsCorp has developed a "smart shell" for the siege tank that scans for allies on impact and adjusts its detonation to minimize damage to friendly units. Field tests have shown that this shell reduces friendly fire fatalities by 75%, though due caution is still recommended when walking into a fire zone.
Attack upgrades improve attack cooldown of affected units by 5% per level.
These self-replicating ultra capacitors reduce the reload time of weapons and systems. Now each of the weapon upgrades at the armory and engineering bay increases attack speed by 5% in addition to increasing damage.
Armor upgrades increase health of affected units by 5% per level.
We have created a new lightweight alloy called vanadium. Vanadium diffuses weapon impacts much more efficiently than traditional armor plating, and it better preserves the life of our units. Now each of the armor upgrades in the armory and engineering bay increases unit life by 5% in addition to increasing armor.
Damaged mechanical units recover hit points when out of combat, at a rate of 0.6015 each second.
Our ship and vehicle hulls are now made from a material called Regenerative Bio-Steel. This material uses internal nanobots to slowly repair any damage the hull sustains. While this regeneration process is much slower than conventional SCV repairs, it can be the difference between life and death if no SCVs are available.
The siege tank was premiered in the 2007 World Wide Invitation, at which much criticism was levied at the tank for its "cartoonish" appearence. One of the earliest revisions once the game went public was making the siege tank grittier and more detailed to appease the fans. Once this was accomplished, there was a stigma on the development team that the siege tank should be left alone as to avoid another backlash. However, this had to be confronted with the development of the Siege Breakers.
In Legacy of the Void, siege tanks could be transported by the medivac while in Siege Mode. They were carried underneath the medivac, visible. A 1.43 second delay occured between dropping and the tank firing. This was removed in Patch 3.8.
↑Getting an army of both is quite expensive - though if you can build the momentum, it is quite difficult to stop this ranged combination. Karune. 2008-05-22. Is terran turtling going to be as powerful. Battle.net StarCraft II General Discussion Forum. Accessed 2008-05-22.