This is for normal difficulty so if you are playing on higher than that let us know.
Alma has 4 attacks- multiple fireballs, flying pillars, a kamikaze dive and a "snatch and grab" attack. Avoid Alma's attacks and use Flying Swallow to inflict damage. If you miss, quickly jump away to avoid the retaliation. When Flying Swallow does connect she falls and is vulnerable for a few seconds- jump in and use Blade of Nirrti to knock the health bar down. Repeat the flying swallow/ blade pattern until defeated.