Rebalance of RG_BACKSTAP (Back Stab)

- Skill mechanics changed
  - No longer needs to be behind the target to use skill
  - No longer ignores accuracy check
  - No longer usable from Hiding state
  - Now increases skill Hit by 4 per skill level
  - Number of hits changed:
    - Old: 1 hit
    - New: 2 hits with Dagger, 1 hit with other weapons
- SP cost reduced: 16 -> 12
- Cooldown added: 0.5s
- Number of hits changed

From massive skills rebalance (1st/2nd/transclass) (2018.10.31)

db/re/skill_db.conf

@@ -6625,7 +6625,7 @@ skill_db: (
 	StatusChange: "SC_STUN"
 	Description: "Back Stab"
 	MaxLevel: 10
-	Range: -1
+	Range: 1
 	Hit: "BDT_SKILL"
 	SkillType: {
 		Enemy: true
@@ -6636,14 +6636,12 @@ skill_db: (
 	}
 	AttackType: "Weapon"
 	Element: "Ele_Weapon"
-	DamageType: {
-		IgnoreFlee: true
-	}
 	AfterCastActDelay: 500
-	SkillData1: 5000
+	SkillData1: 5_000 // Stun duration (in miliseconds)
+	CoolDown: 500
 	FixedCastTime: 0
 	Requirements: {
-		SPCost: 16
+		SPCost: 12
 	}
 },
 {

src/map/battle.c

@@ -4799,6 +4799,11 @@ static struct Damage battle_calc_weapon_attack(struct block_list *src, struct bl
 				break;
 
 #ifdef RENEWAL
+			case RG_BACKSTAP:
+				if (sd != NULL && sd->weapontype == W_DAGGER)
+					wd.div_ = 2;
+				break;
+
 			case KN_BOWLINGBASH:
 				wd.div_ = 2;
 
@@ -5167,6 +5172,11 @@ static struct Damage battle_calc_weapon_attack(struct block_list *src, struct bl
 				if (sd != NULL && pc->checkskill(sd, AS_SONICACCEL) > 0)
 					hitpercbonus += 50;
 				break;
+#ifdef RENEWAL
+			case RG_BACKSTAP:
+				hitrate += 4 * skill_lv;
+				break;
+#endif
 			case MC_CARTREVOLUTION:
 			case GN_CART_TORNADO:
 			case GN_CARTCANNON:

src/map/skill.c

@@ -4996,6 +4996,7 @@ static int skill_castend_damage_id(struct block_list *src, struct block_list *bl
 			status_change_end(src, SC_BLADESTOP, INVALID_TIMER);
 			break;
 
+#ifndef RENEWAL
 		case RG_BACKSTAP:
 			{
 				enum unit_dir dir = map->calc_dir(src, bl->x, bl->y);
@@ -5010,6 +5011,29 @@ static int skill_castend_damage_id(struct block_list *src, struct block_list *bl
 					clif->skill_fail(sd, skill_id, USESKILL_FAIL_LEVEL, 0, 0);
 			}
 			break;
+#else
+		case RG_BACKSTAP: {
+			// Finds out where the unit will be after using the skill
+			enum unit_dir dir = map->calc_dir(src, bl->x, bl->y);
+			if (Assert_chk(dir >= UNIT_DIR_FIRST && dir < UNIT_DIR_MAX)) {
+				map->freeblock_unlock(); // unblock before assert-returning
+				return 0;
+			}
+
+			short x = bl->x + dirx[dir];
+			short y = bl->y + diry[dir];
+			if (unit->move_pos(src, x, y, 1, true) != 0) {
+				clif->skill_fail(sd, skill_id, USESKILL_FAIL_POS, 0, 0);
+				break;
+			}
+
+			clif->slide(src, x, y);
+			clif->fixpos(src);
+
+			skill->attack(BF_WEAPON, src, src, bl, skill_id, skill_lv, tick, flag);
+		}
+			break;
+#endif
 
 		case MO_FINGEROFFENSIVE:
 			skill->attack(BF_WEAPON,src,src,bl,skill_id,skill_lv,tick,flag);
@@ -6407,13 +6431,15 @@ static int skill_castend_id(int tid, int64 tick, int id, intptr_t data)
 				break;
 		}
 
-		if(ud->skill_id == RG_BACKSTAP) {
+#ifndef RENEWAL
+		if (ud->skill_id == RG_BACKSTAP) {
 			enum unit_dir dir = map->calc_dir(src, target->x, target->y);
 			enum unit_dir t_dir = unit->getdir(target);
 			if (check_distance_bl(src, target, 0) || map->check_dir(dir, t_dir) != 0) {
 				break;
 			}
 		}
+#endif
 
 		if( ud->skill_id == PR_TURNUNDEAD ) {
 			struct status_data *tstatus = status->get_status_data(target);

src/map/status.c

@@ -989,7 +989,9 @@ static int status_check_skilluse(struct block_list *src, struct block_list *targ
 			switch (skill_id) { //Usable skills while hiding.
 				case TF_HIDING:
 				case AS_GRIMTOOTH:
+#ifndef RENEWAL
 				case RG_BACKSTAP:
+#endif
 				case RG_RAID:
 				case NJ_SHADOWJUMP:
 				case NJ_KIRIKAGE: