✅ Duban fused as top card

Category	Ability
Status	Passing
Test	tests/test_abilities_passive.py::test_duban_fused_as_top_card

Duban is fused as the TOP card over Murmur. Duban's own passive

Preconditions

• Lane 0: P1's fused demon — top=Duban (#001), bottom=Murmur (#002)

• Duban passive: +5 DEF

• Murmur passive: -2 AP Cost

Action

• Query get_effective_def(state, fused_demon)

result = get_effective_def(state, fused_on_field)

Expected Postconditions

• Returns 5 (Duban's +5 DEF from top card)

Assertions

assert result == 5, f"Expected DEF=5 (Duban top passive), got {result}"