To optimize creeping routes, it's important to be aware of how interactions with creeps work in the game. In this article, we'll take a look at how the creep's aggro works as well as when and how they use their different abilities.
Before we dive in I want to give a little head's up. If you prefer watching videos as a media over written guides, I encourage you to watch carsoNNN's guide on creeping as there will be many overlaps between the two guides.
When talking about aggro range we distinguish between aggressive and passive creep camps. Aggressive creeps will be much more inclined to seek out units and - especially - buildings near them. This is especially important for Night Elf which want to Ancient of War creep. A general rule of thumb is that all creeps who protect a gold mine will be aggressive and other creeps will be passive, so you more safely can build near them.
Creeps will prioritize to attack units that are a threat to them. This allows you to manipulate which of your units will be attacked. You do this by issuing an attack with the attacked unit onto one of your other units. Your initial unit will no longer be viewed as a threat and the creeps will therefore change their target. Once the target has been changed you can safely resume to attack the creeps again.
This does not always work as level 7+ creeps are a bit different as they will tend to attack injured units within their range over healthy ones.
In this chapter, I cover the five most common triggered abilities that you should know how to manipulate.
Lightning Shield can be triggered by Renegade Wizards, which you'll encounter on Terenas Stand and Amazonia. This ability benefits you a whole lot as its effect also damages creeps. When the Renegade Wizard is attacked from afar, it will cast Lightning Shield on any unit that is touching at least two of your other units. As Ancient of War (AoW) is included in said unit count, Night Elf oftentimes trigger the effect by placing an Archer between the AoW and a Wisp before attacking the Wizard with the Archer.
Needless to say, you'll want to move your Archer away once she's received the Lightning Shield by moving her between the creeps. This way you'll be able to speed up your creeping significantly. The Archer won't be attacked as creeps always prioritize attacking buildings (like your AoW).
Human players who creep these type of camps will also oftentimes want to trigger the ability to speed up their creeping. They do, however, use it a bit differently compared to Night Elf. Due to their army consists of Footmen and Militia, who both are melee, they cannot really run around among the neutral creeps with Lightning Shield without damaging their own kin. Therefore, they send the Archmage to a nearby small camp after Lightning Shield has been triggered. They trigger Lightning Shield with the same maneuver as Night Elf, just replacing the unit with Archmage and Footmen and/or Militia.
When creeping with Lightning Shield you should be very careful not to last-hit units with the effect as that won't grant you any experience due to Lightning Shield having been cast by Renegade Wizard and not by one of your own units.
Knowing how Purge works is very important when creeping with summoned units from Far Seer, Beastmaster, and Archmage. If Purge hits a summoned unit, it will deal 400 damage, so it's a big hit on your creeping efficiency. Purge is cast by Renegade Wizard and Gnoll Warden. If you are attacking with an army that contains a summoned unit with 200 HP or higher, said unit will be purged unless another unit becomes the target. Remember how creeps prioritize to attack units that poses a threat to them? Well, the same principal goes for Purge and summoned units! So you should, as an example, summon a Water Elemental and use the move-command and click a creep and then attack the creeps with the rest of your army. This will cause the Water Elemental to stand in front of the creeps without attacking them. The creep will then use Purge on one of your other units and when it has done so, you can safely begin attacking with the Water Elemental. You may wonder why it's smart to summon the Water Elemental first instead of just summoning it after the creeps used Purge. Here's why: Creeps tend to prioritize summoned units with attacks (not spells like Purge) even though they are not a threat, so the Water Elemental will soak up damage from the creeps while your army attacks. Even though this is their tendency there's (as always) exceptions. Because creeps will also focus the unit that gets purged. On the picture below, they'll start attacking the purged footman. To switch their target to the Water Elemental, simply pull away the Footman a bit before resuming to attack with him.
The Envenomed Weapon effect from creeps is one of the easier interactions to wrap your head around due to it being a passive effect on the creep rather than an activated ability. Creeps with Envenomed Weapons include Gnoll Assassin and Murloc Nightcrawler. These creeps will try to inflict poison onto as many as your units as possible, so instead of attacking one unit continuously until it dies, they'll try to attack all your units once. So if you have a Healing Salve running on a unit make sure to keep it away from the fight, so it doesn't get cancelled. Furthermore, if you are creeping with many small units (like Militia), it can be a good idea to focus the creep with Envenomed Weapon fast, so it doesn't get to attack all your units before it dies.
This ability can often be bothersome as it renders your units close to useless and very vulnerable if the enemy is nearby. Thankfully it's quite easy to play around. Ensnare can be used by Murloc Huntsmen and Forest Troll Trapper. Ensnare is cast on non-hero units that enter the creep's cast range (this includes summoning units). If a unit is within the cast range while the camp is being started, it therefore won't be ensnared. In the picture below, a Grunt and the Blademaster are fighting a creep camp. The ensnared Grunt tried to join the fight afterwards, but got ensnared.
It is especially important to keep Ensnare in mind when you are trying to creep jack the opponent as they'll be able to take out your ensnared units very easily.
Creeps won't attack ensnared units unless they can attack the creeps themselves. Additionally Ensnare from creeps cannot target heroes.
When a Rock Golem or Granite Golem is disturbed by a threatening unit it'll cast Hurl Boulder, which damages and stuns the target. The Golem will prioritize to target hero units that are attacking it. To avoid the Golem from using the ability a small, interesting trick has been discovered, which works with (almost) all creep abilities. If the Golem is attacked while it's running back to its camp, it won't trigger the ability. To accomplish this, you have to run near the Golem with a unit and pull it away from the creeps. That way the entire camp will follow your unit until they reach their max aggro range. Make sure not to attack the camp with your unit as the Golem in that instance will view your unit as a threat and thereby cast Hurl Boulder. This method is oftentimes quite inconvenient, so you won't always see it being used.
Night Elves do, however, utilize it when creeping the Mercenary camp on Twisted Meadows with Ancient of War. A Wisp is used to pull away the creeps and an Archer then attacks them when they are returning as demonstrated on the picture below.