The innumerable uses of Arcane Eye

At first, Arcane Eye looks like a rather useless spell to invest generic points into. Reveals monsters for a few turns? Surely there's better uses of generic points. But with a bit of experimentation it quickly turns out to be a fascinating spell; much like duct tape, its uses are limited only by your own imagination. This guide covers several of those potential uses for an easily-obtained and incredibly useful utility spell.

What is Arcane eye?

Arcane Eye is the first spell in the generic tree Spell / Divination, which is available to most classes that start with Mana as their primary resource: Shadowblades, Archmages (naturally), and Necromancers. (or at least they used to).

You can also obtain the spell itself, or the Divination tree, from Lost Seer escorts. Finally, certain item egos (notably the 'Brotherhood' ego) can also provide the spell.

The description itself is straightforward:

"Summons an ethereal magical eye at the designated location that lasts for [X] turns.
The eye cannot be seen or attacked by other creatures, and possesses magical vision that allows it to see any creature in a [X] range around it.
It does not require light to do so, but it cannot see through walls.
Casting the eye does not take a turn.
Only one arcane eye can exist at any given time.
At level 4, if cast on a creature it will follow it until it expires, or until the creature dies.
At level 5, it will place a magical marker on the creatures, negating invisibility and stealth effects."

When you cast it, you pick a square, and the eye appears. You can see it as a disembodied purple-and-white eye, so you won't forget where you put it down.

Why is it such a good spell?

Even if you only get it by taking 1 level from a Lost Seer escort, Arcane eye can prove very useful. The duration and vision radius increase with talent level, but the cooldown stays the same, so it doesn't take much to let you keep Arcane Eye going constantly.

It's also a very cheap spell, about 15 mana (depending on Fatigue, of course). However, there are some features of the spell that make it much nicer than it first appears.

The first is the line tucked in near the end of the description: "Casting the eye does not take a turn." Indeed, it is an instantaneous spell, so even in the middle of an extremely dangerous situation you can put out an Arcane Eye without worry.

There is another feature not mentioned: You do not have to be able to see the square you are targeting. This means that you can use Arcane Eye to scout ahead, by casting it around corners or through walls and doors. In fact, it also works inside of unopened vaults. Not sure whether it's worth cracking open that Dreadfell vault or not? Toss in an Arcane Eye and see what's waiting for you. Maybe it's some orcs, and you can bust inside; or maybe it's a Patchwork Troll or four Radiant/Luminous Horror packs, and you just saved yourself a painful death. About to dig through a wall, but not sure what's on the other side? Use an Arcane Eye to find out.

Additionally, despite the listed range being 'melee/personal', it appears to have a nigh-infinite range. Even though you can only have one Eye active at a time, you can look at anywhere on the level you are on. If you are extremely patient, you could scout out an entire level this way in order to find where randomly-placed bosses are located.

It has a reasonably long duration, somewhere between 10 and 30 turns depending on the talent level. This is particularly useful as an early-warning system if you're hiding in a corridor or side room - set up the eye at the entrance to your hidey-hole and keep an eye out (so to speak) for anyone coming to ruin your day. This is especially useful if you just teleported away from something unpleasant (say, a boss or nasty rare) as they always seem to know exactly where you are hiding, and this way you'll see them coming before they are in firing range.

Higher talent level bonuses

However, the two extra bonuses at talent level 4 and 5 really make the spell shine. Note that that's the effective talent level, so you might get these earlier with a high category mastery, and not at all with a lower mastery.

At level 4, if cast on a creature it will follow it until it expires, or the creature dies. If the target dies, the Arcane Eye does not end - it simply stays in the square where the target died until it runs out. This is incredibly useful when you are about to teleport away from something nasty. Because Arcane Eye doesn't take a turn to cast, you can drop an Eye on whatever you're most afraid of, and then teleport away. You'll be able to see it coming for the duration of the spell, which helps you to move further away from it until you're fully recovered. If you left behind a Damage-Over-Time effect of some sort, you can see if it finishes off the target or things around it, as you still get messages in the game log for things the Arcane Eye sees.

It's also worth noting that you don't have to see the creature for this effect to work when you cast it. If you want to transfer Arcane Eye from one target to another, re-cast it on the same target, or target someone you can't see but know is there (such as fixed-spawn bosses, like the Shade), you can target them and it will follow them around. Combine this with the effectively limitless range of the spell, and you can spy on someone indefinitely.

Finally, the target doesn't have to be hostile for this to work. Tired of having escorts wander around blind corners from you? Put the Arcane Eye on THEM, and you'll know exactly where they are. This is even more useful if you need to teleport/phase door the escort out of a dangerous situation. If you have allies or summons, this lets you watch them from a safe distance.

The level 5 ability lets it negate stealth and invisibility. This has obvious uses, and since Arcane Eye is instant-cast, you can drop one down as soon as you are hit by, or bump into, an invisible/stealthed creature. No need to bother with Keen Senses or Piercing Sight when you have good ol' Arcane Eye at your disposal!

You can combine this with the level 4 ability, as both are active together. You can put the eye on the stealthed creature to follow it around. But, even better - cast Arcane Eye on YOURSELF! It will follow you around diligently, revealing stealthed/invisible enemies. Better yet, its vision range will be much further than yours in dark areas, effectively giving you Heightened Senses for free.

Other tricks

Since Arcane Eye can probably see further than you, you can use it to extend your vision range in long dark corridors (like The Maze or Reknor). Cast it ahead of yourself and see if that rogue you spotted is alone or not.

You can also do away with your light source and rely on a level 4+ Arcane Eye on yourself, if you want to be able to use Invisibility.

You can cast it on enemies before you teleport them away, to see where they went, or the path they're taking to get back to you.

Also, if there's a monster you have no intention of fighting, you can keep an eye on it with Arcane Eye. Solipsist rares, or end-game uniques come to mind.

Also worth noting: Arcane Eye cannot see through walls. But if you cast it on a wall, it will be able to see into, and through, empty squares around it.

Many spells have ranges far greater than sight range, either from raw range or because they hit a massive area (Fireflash or Chill of the Tomb, for instance). Arcane Eye can help you nail enemies you wouldn't normally be able to see.

You can also use it when using summons to scout. Summoners themselves would normally control their summons directly, but others with summons or companions (Alchemist golem, Necromancer harmless bunnies) or item-based summons (spider sac) could find some use by putting an eye on their summons and then letting them roam or teleporting them around.

Since you can use it to see undesirable creatures coming, it can be possible to hit them without ever letting them get in range - the Chronolith twins come to mind, since they are in a wide open area. Hit them with long-range spells from outside their vision range, and keep moving back with Phase Door or Teleport.

When you are blinded, you cannot see any monsters, even with Arcane Eye. However, you can still see the Arcane Eye marker itself, so you can use it to track a targeted monster with a level 4+ Arcane Eye. Also, it does reveal the monsters, just not their tiles - if you move your mouse around, you can hover over monster tiles to see them. In dark areas, Arcane Eye will light the monster's tile while you're blinded.

Finally, when Arcane Eye reveals a monster, it also reveals the terrain and items in the same square. This is useful in vaults that are packed with both items and horrible things (Daikara vaults, for instance). Are there just infusions in there, or is there an artefact at Burb the Snow Giant Champion's feet? Are those luminous horrors standing on a lava field?

Suggestions welcome!

Have you got another interesting use for Arcane Eye? Post a comment, and it'll get added in to this guide!

From Velorien: Arcane Eye is great for adventurer parties and ziguranth ambushes. You can use Arcane Eye to locate the enemies, and strike them from outside sight range, aggroing only one of them at a time. You can also locate safe spots to move to if things are dangerous, either with teleports, movement infusions, or similar abilities; similarly, you can keep out of LOS if you need time to have talents/infusions come off cooldown. This makes overmap encounters much less dangerous than they usually are.

From Velorien: Arcane Eye is also great for detecting targets you need to eliminate quickly - Ben Cruthdar for Fast Curse Dispel being a prime example. Others include the slavers in the arena of blood (for Thralless), the Sect of Kryl-Feijan's priests you have to kill to save Melinda, and literally any enemy that pulls you into the Fearscape.

From Velorien: You can easily keep Arcane Eye up by setting it to auto-cast when no monsters are visible. This might consume a fair bit of mana, but you can also auto-use a manasurge rune unless you're worried about it being unavailable at an important time.

[Kyo]

Thank you for putting this up and taking the time to explain something that most people would not even think of using. I can already imagine a few new ideas using this spell along with a mage classes can't wait to try this out.

[LanceYosh]

♫I can see clearly now that I understand this spell~♫

[Endy73]

Thank you. Very useful.

[Super Arthritis ⁧⁧ ⁧⁧Man]

I see now.

[The Eekexexecycle]

im too chad for this guide i dont need it

[Shaaria]

I wrote this 7 years ago, so it must have changed since then. I should play ToME again some time and make sure this is all still up to date, but for now I will update that.

[Thaxlsyssilyaan]

Necromancer don't have the divination tree.

[CoalWhite]

I have over 600 hours in this game, and only now do I see this and consider the usefulness of this spell. I may try it still. The death's that could have been avoided! Well done, Sir.

[Orange George]

Found this out myself playing as a non magic rogue and started going magic on MANY subsequent playthroughs as a result.

[An Innocent Coconut]

Excellent guide, I've severally underestimated this spell