Manasteel, Elementium, and Terrasteel armor block all incoming damage regardless of the source. Fall damage, piercing damage, explosions, everything gets blocked where it goes right through everything else. This happens in every version of Botania that has the armor from at least R1.6-160 to R1.6188.

How to replicate: Put on any kind of Botania armor, find a cliff, and jump off. The armor will block fall damage. This is true of TNT blasts and Tinkers' Construct rapiers and void damage and any other kind of damage the game usually treats as unblockable. Test with diamond armor for comparison.