What do you get for winning a … H China Grand Campaign war in CK3?

… gains the contested Title (patch 1.20.0.3).

What does the … H China Grand Campaign casus belli cost?

prestige; the amount depends on the titles, claims and distance, worked out when you declare.

Casus belli · Celestial

… H China Grand Campaign

The war is called “… H China Grand Campaign”

… H China Grand Campaign is a casus belli in Crusader Kings III (celestial). If the attacker wins: … gains the contested Title. If the defender wins: The defender keeps the contested Title. Declaring it costs prestige. The war goal is worth 80% war score. Patch 1.20.0.3, from game/common/casus_belli_types/10_tgp_china_wars.txt.

Quick answers (3)

What do you get for winning a … H China Grand Campaign war in CK3?: … gains the contested Title (patch 1.20.0.3).
What happens on a white peace?: The defender keeps the contested Title.
What does the … H China Grand Campaign casus belli cost?: prestige; the amount depends on the titles, claims and distance, worked out when you declare.

How the war ends

Attacker wins

… gains the contested Title.

White peace

The defender keeps the contested Title.

Defender wins

The defender keeps the contested Title.

If the war becomes invalid

The … has ended: the defender no longer … any land in the target region.

Who can declare it

The game shows no text of its own for these conditions; the script is below.

Every celestial war (the group's allowed_for_character) (6 lines of game script)

herders_and_tributary_constraints = yes
pam_personal_pacifism_offensive_war_ban_trigger = yes
tgp_war_ban_civilian_ministers_trigger = yes
NOT = {
	government_has_flag = government_is_theocracy
}

As written in game/common/casus_belli_groups/00_casus_belli_groups.txt.

Attacker (allowed_for_character) (18 lines of game script)

title:h_china.holder ?= {
	OR = {
		this = root.top_liege
		this = root
	}
}
any_great_project = {
	great_project_type = grand_campaign_project
	great_project_owner = root.top_liege
	OR = {
		any_contribution = {
			contributor = root
		}
		root = {
			has_title = title:e_minister_grand_marshal
		}
	}
}

As written in game/common/casus_belli_types/10_tgp_china_wars.txt.

Defender (allowed_against_character) (17 lines of game script)

any_great_project = {
	great_project_type = grand_campaign_project
	great_project_owner = title:h_china.holder
	any_in_list = {
		variable = grand_campaign_titles
		holder ?= {
			OR = {
				this = scope:defender
				any_liege_or_above = {
					this = scope:defender
				}
			}
			this != title:h_china.holder
			top_overlord != title:h_china.holder
		}
	}
}

As written in game/common/casus_belli_types/10_tgp_china_wars.txt.

When it can start (valid_to_start) (5 lines of game script)

any_great_project = {
	great_project_type = grand_campaign_project
	great_project_owner = root.top_liege
	var:grand_campaign_target_kingdom ?= scope:target
}

As written in game/common/casus_belli_types/10_tgp_china_wars.txt.

Cost to declare

Costs prestige. The amount is worked out when you declare (by the titles targeted, claims, distance and more), so the script is shown as written:

Cost (13 lines of game script)

prestige = {
	add = {
		value = 50
		desc = CB_BASE_COST
	}
	add = {
		value = 2.5
		multiply = scope:attacker.realm_size
		desc = CB_REALM_SIZE_COST
		max = 150
	}
	multiply = common_cb_prestige_cost_multiplier
}

As written in game/common/casus_belli_types/10_tgp_china_wars.txt.

Source: game/common/casus_belli_types/10_tgp_china_wars.txt and the English localisation, Crusader Kings III 1.20.0.3. “The attacker”, “the defender” stand where the game names the character; “…” marks other words it fills in during play.