Why does Hidden Blade fail to draw cards when its target dies before resolution, but Discipline still draws a card when its target dies or is removed?

Ruling: Hidden Blade fails to draw cards when its target dies because "its controller" cannot be referenced once the target no longer exists. Discipline still draws a card because it uses "draw 1" (referring to the caster) rather than "its controller" (referring to the target).

Nuances:

• The difference is in the card text wording: "draw 1" vs "its controller draws 1"
• When a card refers to "its controller" (meaning the target's controller), it needs the target to exist to determine who draws
• When a card says "draw 1" without reference to the target, the caster draws regardless of whether the target still exists