The adamant prioritizes the many over the few. They use their shield to protect all their fellows and prevent harm coming to their companions. Adamants should focus on their constitution and maintaining proximity with the more fragile members of the party.

Great Armor

Beginning when you choose this archetype at 3rd level an Adamant gains resistance to slashing damage as long as they are wearing medium or heavy armor. 

Instant Bulwark

Starting at 7th level any time an ally within 50ft is attacked or targeted with a touch spell an Adamant can, as a reaction, appear adjacent to their ally. If the Adamant has the protection fighting style they impose disadvantage on the attack or spell that provoked the reaction.

Immediate Intercession

Adamants know that they are far hardier than the majority of their comrades. Starting at 10th level they may choose to fail their save against any area of effect that deals damage to grant adjacent allies resistance to all damage from that effect. 

Great Shield

At 15th level endless experience has provided the Adamant with a great deal of insight into defense, the Adamant may add half their proficiency bonus to their AC provided they are wearing heavy armor if they ever lose their armor or are helpless, they lose this bonus to their AC.

Undying Resistance

At 18th level an Adamant gains resistance to all damage from spells and magical effects (i.e. a fireball or a dragons breath weapon)