CustomMob.java

    public static boolean attemptSpawn(Entity entity) {
        Location loc = entity.getLocation();

        long now = System.currentTimeMillis();
        if (now - lastSpawnAttempt >= 200) {
            lastSpawnAttempt = now;
            final MetaApi.MetaMap worldMetaMap = MetaApi.getWorldMetaMap(entity.getWorld());
            for (CustomMob customMob : spawnableList) {
                String metaKey = "survivalRespawn_" + customMob.customType;

                final Object o = worldMetaMap.get(metaKey);
                Long nextSpawn = o instanceof Long ? (Long) o : now;

                if (customMob.spawnRate == 0 || nextSpawn > now) {
                    continue;
                }

                if (!customMob.canSpawn(loc)) {
                    continue;
                }

                float randChance = Util.RANDOM.nextFloat() * 100;
                if (randChance > customMob.spawnRate) {
                    continue;
                }

                boolean tooClose = false;
                for (Entity playerCheck : entity.getNearbyEntities(customMob.minPlayerSpawn,
                    256,
                    customMob.minPlayerSpawn)) {
                    if (playerCheck instanceof Player) {
                        tooClose = true;
                        break;
                    }
                    if (playerCheck.getType() == customMob.baseType) {
                        if (getType(playerCheck) == customMob) {
                            tooClose = true;
                            break;
                        }
                    }
                }
                if (tooClose) {
                    continue;
                }

                if (Wastelands.isWastelands(entity.getWorld())) {
                    if (Wastelands.isSpawnVicinity(entity.getLocation(), 64)) {
                        continue;
                    }
                }

                // Finally can spawn
                nextSpawn = now + Util.rand((int) (customMob.respawnRate * 0.9), (int) (customMob.respawnRate * 1.1));
                worldMetaMap.put(metaKey, nextSpawn);
                customMob.spawn(loc);
                return true;
            }
        }
        return false;
    }