Decay Ward

Minions have +18% Chance to Block Attack Damage
Minions have +18% Chance to Block Spell Damage
Minions Recover 2% of their Life when they Block [1]

Decay Ward is a notable passive skill that grants additional chance to block attack and spell damage for minions, as well as percentage life recovery on block for your minions.

Anointment

Blight anointment to unlock the passive:

Oil #1	Oil #2	Oil #3	Outcome
Sepia Oil	Verdant Oil	Teal Oil	Decay Ward	Minions have +18% Chance to Block Attack Damage Minions have +18% Chance to Block Spell Damage Minions Recover 2% of their Life when they Block

Version	Changes
3.16.0	[Undocumented This change was not documented by any official sources. It was discovered through player testing or datamining.] Now grants Minions have +18% Chance to Block Attack Damage (up from 10%). Now grants Minions have +18% Chance to Block Spell Damage (up from 10%).
3.8.0	Mine passives, Damage over Time passives, Mana passives and Summoner passives have also extensively change. Now grants Minions have +10% Chance to Block Attack Damage (up from 4%). Now grants Minions have +10% Chance to Block Spell Damage. No longer grants Minions Recover 1% of their Maximum Life when they Block. Instead, it now grants Minions Recover 2% of their Life when they Block.
3.7.0	Decay Ward and the preceding small passives have been moved from behind Necromantic Aegis to across from it.
3.4.0	Chance to Block and Chance to Block Spells have been reworked. Previously there were several different modifiers that applied in different ways but achieved the same thing. No longer grants Minions have +4% Chance to Block. Instead, it now grants Minions have +4% Chance to Block Attack Damage.
2.0.0?	Introduced to the game.