May 17, 2023
Cast when Damage Taken: Everything you need to know
A guide to Cast when Damage Taken in Path of Exile.
Some of you may not know, but I’m actually one of the first player to do Ward loop Cast When Damage Taken back in 2021, and every once in a while I still get questions about it from my chat while live streaming. So I decided to write a guide about Cast When Damage Taken, including mechanics, strategies, and tips.
Cast When Damage Taken
Cast When Damage Taken (CwDT) is a support gem that casts ALL linked spells when the player takes a certain amount of damage.
Note: The damage counter won’t be counting while the spell is on cooldown.
The gem has a level requirement, and the spells linked to it must be below that level. For example:
- Giving a level 15 CwDT has a level requirement of 65
- level 17 Ice Spear has a level requirement of 64, in this case Ice Spear can be linked to CwDT.
- level 18 Ice Spear has a level requirement of 66, in this case Ice Spear cannot be linked to CwDT.
The gem also has a cooldown, which is shared between all spell with the same name no matter where it is socketed. The cooldown started at 250ms and is affected by cooldown recovery speed.
Heartbound Loop is a unique ring that will deal 350 physical damage to you for every one of your minions that dies.
Now, if you have summon skeletons linked to CwDT, you can have a loop of skeletons dying and being summoned, which will trigger Heartbound Loop and deal damage to you. This will trigger CwDT, which will summon more skeletons, and the loop continues.
You can try this in your hideout by linking level 1 CwDT to Summon Skeletons and put on Heartbound Loop, and then try summoning skeletons (from other gem). You will see that when the skeletons expire, they will trigger Heartbound Loop, which will trigger CwDT, which will summon more skeletons.
Note: The damage from Heartbound Loop can be increased by quality on the ring. The damage is also affected by your physical damage reduction, so be sure not to have too much armor when trying this.
But you will also notice that the skeletons died too slowly, and the loop is not fast enough to be useful. This is because the skeletons have a duration of 20 seconds, and the cooldown of CwDT is 250ms. So we need to find a way to make the skeletons die faster.
Which can be done by linking the skeletons to Anomalous Minion Speed Support, this version of the gem will reduce the duration of the skeletons by 2% per quality. So with 20% quality, the skeletons will have 40% reduced duration.
Now, if you try the loop again, you will see that the skeletons die a bit faster. But it is still not fast enough, so we need to find a way to make the skeletons die even faster.
Skeletons duration also affected by skill effect duration, so you can allocate the skill effect duration nodes on the tree to reduce the duration even further. There’re a total of 25% reduced duration on the tree below the Scion start, combining with the 40% reduced duration from Anomalous Minion Speed, the skeletons will have 65% reduced duration.
There’re still 35% duration left, which can be reduced by using To Dust unique jewel. This jewel have a 10-20% reduced duration of summoned skeletons, so you grab two of these jewels, with 17% each, and you will have 34% reduced duration, which is enough to make the skeletons have only 1% duration left.
Note: The duration of the skeletons cannot be reduced to zero, so you will need to have some duration left.
Now, if you try the loop again, you will see that the skeletons die almost instantly, but the loop stop working. This is because the skeletons have only 1% duration left, which is 200ms, and the cooldown of CwDT is 250ms. That mean the skeletons will die before CwDT can summon more skeletons, preventing the loop from happening.
In order to fix this, we need to increase the cooldown recover speed of CwDT. Which can be done by using Belt/Boots with cooldown recovery speed, and also on Anomalous Temporal Rift skill. In order for CwDT to catch up with 1% duration of skeletons, you will need at least 9% cooldown recovery speed.
Note: Some of you may notice that 9% cooldown recovery speed will make CwDT have 229.36ms cooldown, which is still slower than the 200ms duration of skeletons. But it is actually enough, because the server tick rate is 33ms, which mean the actual duration of skeletons is 231ms.
Now that the loop is working and is fast enough, you will notice that you will take a lot of damage from Heartbound Loop. This is where Ward comes in.
Ward is a new mechanic introduced in Expedition league. It is a yellow bar above your Life bar, which will disappear when you take damage and reduce the damage you take by the amount of Ward you had. Ward will regenerate all at once after a short delay.
Unlike armour, Ward won’t reduce the damage you take to zero, so you will still take damage from Heartbound Loop. But it will protect your life from the otherworldly damage you take from the loop.
But wait, didn’t I say that the ward will disappear when you take damage? Yes, but there’s a way to prevent that from happening. Which is by using Olroth’s Resolve flask, which will prevent ward from disappearing during flask effect.
So if you try using Olroth’s Resolve flask, you will see that the ward will stay up, and you will take no damage from Heartbound Loop. But you will also notice that the ward will disappear after the flask effect end, and you will take damage from Heartbound Loop again.
You can prevent that by crafting “Reused at the end of Flask Effect” on the flask, which will make the flask effect last forever, if you can sustain the flask charges.
This can be achieved by a combination of lots of thing, including but not limited to:
- The Traitor (Keystone) which gives 4 Flask Charges every 5 seconds for each empty Flask Slot. You can get this keystone by using the unique jewel Brutal Restraint with mod that said “Denoted service of # dekhara in the akhara of Balbala.” (find in trade)
- “Reduced Flask Charges used” and “Increased Flask Effect Duration” on belt. (find in trade, this search is on Stygian Vise, try searching for one that have suffix slot open to be crafted with “Increased Cooldown Recovery Speed”)
- Being a Pathfinder, or Ascendant with Pathfinder Ascendancy, which will give you 3 Flask Charges every 3 seconds.
- The Searing Exarch Implicit “Gain 2 Flask Charges every 3 seconds” on Body Armour. (Not recommended post nerf, the global defense on Grasping Mail is now only 50%)
- Flask passive nodes on the tree. (Beware of the node with “Flasks applied to you have #% increased Effect” mod, it will increase the mod on Olroth’s Resolve, which will reduce the amount of ward you have)
- Flask passive from Cluster Jewel. (Fasting, Distilled Perfection, etc.)
Because we are taking a huge amount of damage from Heartbound Loop, we can take advantage of that by using Recoup mechanic. You can even use it to sustain the RF degen without any life regen. This also fix our mana problem.
Cooldown Cheat Sheet
|CDR||Cooldown||Duration||Additional Gem/Passive||DPS vs. No CDR|
|0%||264 ms||-98%||lv1 Less Duration|
|27%||198 ms||-99%||10% Less Duration Mastery||+33.33%|
|52%||165 ms||-99%||Swift Affliction||+60.00%|
|90%||132 ms||-99%||lv1 Less Duration||+100.00%|
90% CDR can be archived by:
- 20% from Belt
- 20% from Boots
- 30% from Saboteur Ascendancy
- 20% from q80 Anomalous Temporal Rift
q80 Anomalous Temporal Rift can be archived by:
- 20% from base gem
- 30% from Ashes of the Stars
- 32% from lv5 Awakened Enhance or lv4 Enhance in +1 socketed gem gear
- or just use lv4 Enhance and add a single CDR Abysmal Jewel
Overall, not worth it, just use 52% CDR.
I’ll make a calculator for this build soon, so stay tuned.