Splinterguard

The protective panels that adorn this splint armor are made from carefully molded pieces of ironleaf lumber, a wood renowned for its remarkable durability. Even if you aren't attuned to the armor, you gain the following benefits: While you're wearing this armor, any critical hit against you becomes a normal hit. In addition, the first time each day you're struck by a critical hit, the armor's panels splinter into countless shards of painful, wooden shrapnel. Other creatures within 10 feet of you must make a DC 15 Dexterity saving throw, taking 3d8 piercing damage on a failed save, or half as much damage on a successful one. Once this happens, the armor's wooden panels are cracked until the following dawn, at which point they magically regrow. Until the panels regrow, the armor can't be splintered again and suffers a –2 penalty to the AC it offers. The panels can't be repaired by magical or mundane means, but a plant growth spell can cause the panels to regrow early once before each dawn. If you're attuned to this armor, you're considered proficient with it, and you don't suffer disadvantage on Dexterity (Stealth) checks you make as a result of wearing it. In addition, creatures hit by the armor's shrapnel when it splinters take 5d8 piercing damage, instead of 3d8, and you can choose which creatures in the area are affected by it when it happens.

This armor is made of narrow vertical strips of metal riveted to a backing of leather that is worn over cloth padding. Flexible chain mail protects the joints.

The wearer has disadvantage on Stealth (Dexterity) checks.

If the wearer has a Strength score lower than 15, their speed is reduced by 10 feet.