Warlord's bloodlust rework

Warlord’s Bloodlust – Reworked

Moving or attacking makes an attack Energized. Energized attacks have 1/1/2/3/5/7/9/12/15/18/21/25/28/32/37/41/46/50% Lifesteal and grant 30% Movement Speed for 0.75 seconds

Now let's say at the start of a fight I have 100% energy and attack someone, is the passive gonna activate and heal me for no reason, or does it at least wait till I lose some form of hp before increasing it? If its the former, this is actually a pretty decent nerf to the overall health gained from Warlords, since you'll probably get one off in a fight on average (Maybe even less than that in this meta lol). However if the passive won't trigger until I've lost at least some hp then that would be pretty good. Cause I know the other energy passives trigger the moment I attack, which is fine since they don't give hp but that's what makes this one weird.

EDIT: Also, isn't this extremely RNG based??? Let'say I'm Caitlyn, the AA that heals me could be a normal AA, a crit, or a headshot crit. Making the healing unpredictable as hell. Isn't that kinda dumb?