; [wDamage] += a
AddToDamage:
	push hl
	ld hl, wDamage
	add [hl]
	ld [hli], a
	ld a, 0
	adc [hl]
	ld [hl], a
	pop hl
	ret

; [wDamage] -= a
SubtractFromDamage:
	push de
	push hl
	ld e, a
	ld hl, wDamage
	ld a, [hl]
	sub e
	ld [hli], a
	ld a, [hl]
	sbc 0
	ld [hl], a
	pop hl
	pop de
	ret