Spheric Guardian is a Monster found in Acts 2 and 3 of the Spire. Its low HP of 20 is counteracted by its high amounts of Block, which it will continue to build up as the fight continues. In order to ensure its tankiness, it starts with Barricade as a buff and 3 charges of Artifact.
The Frail debuff this enemy applies can be very dangerous when combined with the large amounts of damage it can dish out. If you can apply debuffs fast enough, applying a Weak debuff or using a card such as Disarm can do a great deal to mitigate these attacks.
In contrast, if you have Turnip or Orange Pellets, the Frail debuff can be completely negated. Thus, gaining enough Block for the enemy's attacks is less challenging.
If this enemy is accompanied by other enemies, it is usually worth killing the other enemies first. While the Spheric Guardian will continue to build Block, dealing with more than one attack while Frail can be overwhelming.
If playing as the Defect, a very useful card in this fight is Melter, which will remove the enemy's Block and deal significant damage, almost effectively ending the fight.