(Quick Effect): You can banish 2 DARK monsters from your GY; banish this face-up card until the End Phase. You can only use this effect of "Strike Ninja" once per turn.
Rulings
Individual Card FAQs
You cannot activate "Strike Ninja"'s effect during the Damage Step.
"Strike Ninja" is a Multi-Trigger effect so you can chain it to another Spell Speed 1 or 2 effect and can activate it outside your Main Phases, even during your opponent's turn (but not during the Damage Step).
You can only activate "Strike Ninja"'s effect when "Strike Ninja" is face-up on the field.
Removing 2 DARK monsters for "Strike Ninja"'s effect is a cost.
Netrep Rulings
If "Strike Ninja" attempts to return to the field when all monster zones are occupied, "Strike Ninja" is destroyed.
"Strike Ninja's" effect only applies while "Strike Ninja" is face up on the field.
The effect of "Strike Ninja" returning to the field after being removed by its own effect is not a Special Summon.
DARK|
Level 4|[ Warrior / Effect ]
ATK 1700|
DEF 1200