Spell Suppression gives a chance to halve spell damage taken. The chance can be stacked up to 100%. It can be found on Evasion items as well the Dexterity section of the Passive Skill Tree.
PoE Spell Suppression
Spell Suppression is designed as the Dexterity character's best answer to spells. In general, Spell Suppression gives easier access and more reliable spell damage mitigation for Dexterity characters without reliance on specific uniques. It's also much more reliable than Spell Dodge, but has a lower maximum. There will be a few specialised ways to invest in increasing the spell damage suppressed to reward high investment if you want to further protect yourself from spell hits.
Spell Suppression will be found on various Passive Skills in the Evasion areas of the Passive Skill Tree.
The Evasion Wheel at the centre of the Passive Skill Tree no longer provides Accuracy, but provides a combo of Evasion and chance to Suppress Spells instead.
New Suffix modifiers have also been added to all Evasion Armours that can roll modifiers that grant a chance to Suppress Spell Damage. Body Armours and Shields in particular can roll larger values of these modifiers.
New Keystone Passive Skill added to the centre of the tree called Magebane: Dexterity provides no inherent bonus to Evasion Rating. You gain a 1% Chance to Suppress Spell Damage per 15 Dexterity.
Vaal Grace no longer has Chance to Dodge Attack Hits or Spell Hits. Instead, it now has +15% Chance to Evade Attack Hits, and “Suppressed Spell Damage dealt to you is Unlucky”.
Additional chance to Evade modifiers were discontinued from all Rare modifiers, passives and Pantheon powers as their values were generally too low or felt out of place and so that Vaal Grace could provide a very large value of this stat.
Change Elusive to provide 15% chance to Avoid Damage from Hits, instead of it's old Dodge-related stats.
Change Wind Dancer to further improve high Evasion builds rather than reducing Evade chance, but making it riskier if you're not Evading attacks a lot. It now gives less Attack Damage taken if you haven't been Hit by an Attack recently, and more Evasion Rating and Attack Damage taken if you have been Hit, so it's better for Evasion characters that have a high Evasion Rating and bad for characters that are being hit a lot. It has no interaction with Spells now, to focus its interaction on Evasion.
Acrobatics has been redesigned. It no longer has any of it's old properties, but now changes any modifiers to Spell Suppression into Spell Dodge at 50% of it's value. The intention is that Acrobatics is the only source in the entire game for Spell Dodge, for characters who would like to benefit from that playstyle still. Spell Dodge is still capped at 75%, and the Keystone Passive will specifically mention this.
Phase Acrobatics no longer exists.
Many other smaller changes on top of those noted above to improve specific items, Passives, and Skills.
Problem: Evasion provides no defence against Spells.
Solution: Introduce "Spell Suppression" on Evasion items as well the Dexterity section of the Passive Skill Tree, which gives a chance to halve spell damage taken. The chance can be stacked up to 100%. Convert existing sources of Dodge and Spell Dodge to Spell Suppression or replace them with other bonuses.
Evasion mitigates Attacks well, so GGG introduced Spell Suppression to help Evasion builds protect themselves against Spells.