Strategy: Long Fei is built around a threshold, not a cooldown — Above and Beyond and Mountain Mover both trigger the moment his Health drops below 50%, and they trigger together: 60% reduced damage taken and 48% increased Attack, simultaneously, right when most heroes would be at their most fragile. He gets more dangerous as the fight goes worse for him, which is the opposite of how most Infantry leads scale.
Ambrosia is the other half of the kit, and its real value isn't the 120% Attack Speed — it's four seconds of full control immunity. Against heroes whose entire kit depends on landing a stun or silence (Jaeger's Fatal Attraction, Sound of Silence), that window means Long Fei simply plays through their combo untouched. Strong Brew (his exclusive skill) extends that window by 1.5 seconds and converts 15% of the damage he deals during it into healing, turning Ambrosia into a genuine sustain tool rather than just an offensive cooldown.
Skill priority: Ambrosia first for the control immunity and uptime, Above and Beyond second since the damage reduction is the bigger survivability lever of the pair, Mountain Mover third.
Compare him to Triton directly: Triton front-loads a proactive invulnerability window at the start of the fight, while Long Fei's survivability is reactive and threshold-triggered, better suited to long garrison defenses that grind on rather than short burst trades. If you haven't unlocked Triton yet, Long Fei isn't a downgrade so much as a different tool — keep using him for defense even after Triton arrives.