Promotions

Every week, there was a promotion offering discounts or increased rewards in Dungeon Keeper. The various discounts included gems, reinforced walls, traps that cost stone and yes, even Imps. This page is to keep track of these different promotions. Promotions lasted one full week.
=Regular Promotions=
==Accelerate Sale==
All Acceleration costs were 50% off. This included rushing Rooms, Traps & Doors, Training minions and Immortals, reviving knocked out/captured Immortals and spawning minions (did not include guild withdrawals or deposits)
*When upgrading the Dark Library, it would stop producing mana, leaving none for the player to collect until the upgrade was complete. While it was upgrading, you couldn't cast spells or gain spell XP, unless you purchased mana with gems. It could be very beneficial to accelerate this building. 
*Accelerating minion summoning could also be very cheap and worthwhile.
*If you were going to accelerate training times (or simply monitor them), training bonuses from guilds were not applied until you watched a replay or looked at another player's dungeon or tested your own dungeon.
*Mines and Quarries did not produce gold and stone while being upgraded. Though the quantity they provided wasn't worth accelerating them for unless you were desperate for Imps.
==Boost Sale==
All boost costs were 50% off. This included First Strike, Cave-In, Fortification, Scouting and DK Premium.
*Cave-In - Cannot be attacked by enemy Keepers. NOTE: Agreeing to an attack against an enemy Keeper will remove this Boost
*First Strike - 120% Attacking minion damage, minion health, minion move speed and spell damage
*Fortification - 120% Trap Damage, Trap Health, Room Damage, Room Health, Defending Minion Damage, Defending Minion Health, Defending Minion Move Speed. NOTE: Health increases do not affect Reinforced Walls.
*Scouting - Reveals all Hidden Traps during raids
*DK Premium - 140% Gems from Exclusive Raids, Gold from Raids, Stone from Raids, Combat Points from Raids, Mana Production, Gold Production, Stone Production.
*At the time of buying, taking advantage of the 20% increase in boost duration required a guild that was at least level 40. This was especially valuable when purchasing DK Premium for 100 days, since you would get a bonus of 20 days.
*Buying the 100 day DK Premium during this sale costed 5000 gems, instead of 10,000.
*On the last day of the sale, you could buy 7-day sales to last you the whole of the next week.
Boost 	NormalCost	PromoCost	Time withno guild perks	Guild PerkLevel 1 - 2%	Guild PerkLevel 2 - 5%	Guild PerkLevel 3 - 10%	Guild PerkLevel 4 - 20%
DK Premium 1 day 	150 	75 	1d 	 	1d 1h 12m 	 	1d 4h 48m
DK Premium 3 days 	400 	200 	3d 	 	3d 3h 36m 	 	3d 14h 24m
DK Premium 7 days 	750 	375 	7d 	 	7d 8h 24m 	 	8d 9h 36m
DK Premium 100 days 	10,000 	5,000 	100d 	102d 	105d 	110d 	120d
Cave-In 1 day 	100 	50 	1d 	 	1d 1h 12m 	 	1d 4h 48m
Cave-In 3 days 	250 	125 	3d 	 	3d 3h 36m 	 	3d 14h 24m
Cave-In 7 days 	500 	250 	7d 	 	7d 8h 24m 	 	8d 9h 36m
First Strike 1 day 	100 	50 	1d 	 	1d 1h 12m 	 	1d 4h 48m
First Strike 3 days 	250 	125 	3d 	 	3d 3h 36m 	 	3d 14h 24m
First Strike 7 days 	500 	250 	7d 	 	7d 8h 24m 	 	8d 9h 36m
Scouting 1 day 	150 	75 	1d 	 	1d 1h 12m 	 	1d 4h 48m
Scouting 3 days 	350 	175 	3d 	 	3d 3h 36m 	 	3d 14h 24m
Scouting 7 days 	700 	350 	7d 	 	7d 8h 24m 	 	8d 9h 36m
Fortification 1 day 	80 	40 	1d 	 	1d 1h 12m 	 	1d 4h 48m
Fortification 3 days	160 	80 	3d 	 	3d 3h 36m 	 	3d 14h 24m
Fortification 7 days	350 	125 	7d 	 	7d 8h 24m 	 	8d 9h 36m
==Trap Sale==
All trap stone costs were 50% off. This includes Spike Traps, Doors, Freeze Traps, Fireburst Traps, Poison Traps, Bug Zappers, Anti Air Traps, Cannon Traps & Dante's Mounds. 
Did not include the Dreadstone purchase cost for Dante’s Mound (which was 250 Dreadstones) and did not include Reinforced Walls; they had their own sale.
Did not include the gold-based traps, which included Spring Traps, Chicken Bomb Traps, Boulder Traps, and U.R. Mines.
*At higher levels, traps could be very expensive.
*Dante's Mounds and Doors were often good choices to upgrade, as they provided the most DCR out of all the traps, and their level was easiest to max out.
==Reinforced Wall Sale==
Reinforced Wall Sale: 60% off Reinforced Walls. Only included Reinforced Walls, which were all instantly upgradable at all levels providing you had one Imp available.
*Upgrading walls that were higher levels would gain you the most benefit. At lower levels, they could be upgraded with ease even without the special.
*During this promotion, gathering stone was very difficult, as most players were spending their stone on walls, leaving little to plunder.
==Spell XP Promotion==
Players could earn double the experience when casting spells. Could sometimes be different quantities; it had been up to quintuple before.
*When you had spare mana and you were not raiding, you could go into campaign dungeons and use spells, then leave. You would still get experience.
==Resource Sale==
Resource Sale: purchasing gold and stone was 35% off.
*This was still very expensive to do, even with the special.
*This promotion didn't scale well with higher level dungeons, and the developers were aware of this, though were not able to fix it.
==Imp Sale==
40% off Imps: reduced the cost of purchasing Imps with gems.
*It was recommended to wait until this promotion occured to purchase Imps.
*Buying your first pack of gems would provide you with one free Imp. This was added instantly and could not be used later.
*It would take you a couple of days of playing regularly from a new account to afford to buy the 3rd Imp without the promo; with the promo, it could be done on the same day easily enough.
ImpCount	Cost(Gems)	PromoCost(Gems)	PromoSavings(Gems)
1st 	Free 	Free 	0
2nd 	200 	120 	80
3rd 	800 	480 	320
4th 	1,200 	720 	480
5th 	2,100 	1,260 	840
6th 	4,200 	2,520 	1,680
Total 	8,500 	5,100 	3400
==Rare Promotions==
===Immortal Sale===
50% off Immortals: Immortals that cost gems to purchase were reduced in cost by 50%; immortals that cost dreadstones were unaffected.
*Immortals that costed dreadstones were not affected by this promotion.
===Guild Event - Free For All!===
Guild Event - Free For All: All Tournament Star bonuses were reduced to 1, including all DCR, Dungeon Heart, League of Evil, and Victory Star multiplier bonuses. The Star count required for a Guild to qualify was reduced to 10 link.
===Specific Spell Bonus and XP Promotion===
Specific spells could receive triple to quadruple the XP. Some also may have got an extra cast. For example, the Disable Trap spell could have 1+ extra cast each time it is used.
*Even if you had maxed the specific spell, you get an extra cast.
===Guild Power Up Event===
Guild Power Up: all Guild Minion Donation and withdraw times were reduced by 50%. This event only occurred once, on the week of 17 September 2019.
===Room Sale===
All rooms were 50% off upgrading except Dungeon Hearts, Guild Lairs, and Guard Rooms.
*This promotion only started appearing four years after the game's release. 
*If you were upgrading other rooms before the sale, and you cancel them, you would only get 25% back of what you spent, as it calculated at the promotion's price, not the one prior.
Times that the Room Sale has occurred:
* Week of 8 April 2020
* Week of 24 December 2019
* Week of 26 November 2019
* Week of 27 August 2019
* Week of 28 May 2019
* Week of 14 November 2018
* Week of 31 July 2018
==Powerup Promotions==
These were fairly common promotions, though each one only occured about once or twice per year.
===Trap Powerups===
*Bug Zapper - Increased damage by 200% link
*Fireburst Trap - Increased damage by 100% link
*Poison Trap - Increased range by +1 link
*Spike Trap - Increased damage by 250% link
*Dante's Mound - No known promotion
*U.R. Mine - No known power up promotion
*Door - No known power up promotion
*Reinforced Wall - No known power up promotion
*Cannon Trap - No known power up promotion
*Anti Air - No known power up promotion
===Minion Powerups===
Specific minions could receive bonuses during this promotion. For example, in August 2018, the Warlock received 1+ Range and 50% bonus DMG.
*This promotion could be good only if the specific minion is at a decent level.
*Could be a good idea to rearrange your dungeon when these promotions occur. For example, a Warlock that can fire over three walls instead of two could yield devastating results, depending on your dungeon.
*Skeleton - No known power up promotion.
*Warlock - Deals +50% damage, Attack speed doubled and weakness to poison removed link or 
*Necromancer - 50% health and raises Warlocks instead of Skeletons. Note: Warlocks did not drop tombstones during this event. link
*Vampire - Increased damage by 150%. link
*Mistress - double health, AoE shock radius and duration doubled, and efficiency duration doubled. link
*Dragon Whelp - Damage increased by 50% on opening attack and does not trigger Freeze Traps or Bug Zappers. link
*Ghost - Increased health by 250% and increased damage by 75%. link
*Bile Demon - Increased health by 40% and increased movement speed by 25%. link
*Troll - Increased health by 25% and increased movement speed by 25%. link
===Immortal Powerups===
Specific Immortals could receive bonuses during this promotion. For example, in July 2018, Deegg & Dugger received double bonus move speed & triple digging damage.
*The benefits of this promotion depended on the Immortal's level.
*When Immortals had a max level of 35, they received a special bonus if you had the immortal at that level.
*Tiny - ?
*Horny - double damage, double AoE range, and double AoE max targets. link
*Mortimer - double speed and double health. link
*Magmaw - ?
*Sir Cophagus - ?
*Deegg & Dugger - Increased movement speed by 50% and increased burrow damage by 50%. link + older link
*Glarggl - Increased health by 50%, increased room disable duration by 50% and mystery bonus for level 40 Glarggls. link
*Swampus - Damage to resource rooms is tripled, takes 75% less damage from traps and buildings, plus a special bonus if it is level 40. link + older link