Complex allergic conditions and evolving diagnostics demand advanced clinical frameworks and specialist-level decision-making. Volume 2 covers biologic therapies, precision diagnostics, perioperative allergy assessment, and the management of refractory or multi-system allergy syndromes. It reviews emerging allergens, occupational exposures, and the role of the microbiome and genetics in allergic predisposition. Chapters provide algorithms for escalation of care, desensitization protocols, and coordination with dietitians and behavioral specialists for food allergy management. Safety considerations--anaphylaxis preparedness, vaccine guidance, and drug allergy evaluation--are emphasized throughout. The volume is intended for allergists, immunologists and clinicians managing high-complexity allergy patients.