The only other I tries was the spike one and that wasn't very useful, Igni only has a real use for lighting campfires without flint.. but Aard kicks ass.. probably one of the most useful features I've seen in any game.. Stun, kill... stun, kill... stun, kill... lol
Igni has more use than just lighting fires.On higher levels, it instils fear, forces enemies away from you, and continues to cause damage if your enemies are incinerated. You just blast them with fire and then stand there and wait for them to burn to death. You don't even need your sword.
On medium difficulty level the use of signs and alchemy is unnecessary. Certainly it adds to the experience, but there are no encounters which may not be solved by swordplay alone.(Naturally you will require the use of the Aard sign in order to destroy various barriers that are found mostly in caves.)
i mainly use Aard and Igni but the others do have a place. The spikes one is very handy if you're fighting in a tight area as you can stand on them and anyone trying to attack you will take damage or you can put them in a narrow passage and everyone is forced to run over them.Aard is very useful when levelled up a bit, you can stun 3 or 4 people in one go which can be the difference between life and death against those stupid scoi'atel elves with the dual blades, and makes fighting ghouls, alghouls, fleders and the like easy as one powered up shot stuns them instantlyand Igni is useful against certain enemies, the bloedzuigers and echinops die very quickly when on fire and it's quite useful against the warrior kikimore as well, plus it's handy when fighting 5 or more salamandra as a few of them out of range of your sword will still take damagei've only used the defensive spell once but it did save my life as i was getting mugged by 5 salamandra and 4 kikimore workers after leaving the inn and messed up the fighting a bit, ended up with about 10% of my health left and no regeneration spell in effect, so i cast that spell and drank the swallow spell, then ran round in circles for a few seconds till my health filled up againThe only one i havent found a use for so far is that one that's meant to make the enemies help you.. it doesn't seem to do anything to anyone whenever i cast it, just some green glow and nothing else..
I've put quite a lot of points into Quen. I just love it, shield up and run into a mob. While they are hitting you they die while you just stand there doing nothing. Or well, prepare... getting a potion ready, grabbing the sword and setting it in the correct mode. Very relaxing while everybody is getting 20% health chopped off every time when hitting you.The one that's meant to make the enemies help you does actually work quite well. Especially with multiple opponents. However you have to stop hitting your opponent after using the spell. When his healthbar on the ground turns blue he will fight for you and most enemies will attack him instead of you.
The one that makes enemies help you can help a big deal ( i believe it's called axii). After completing the quest on the tower in the swamp you get this fight with jazed and the prof. I put the axii sign on the prof who started hitting Jazed. Jazed would have died swiftly if not for the cut scene....
it depends mostly on the medails you distribute. I think axii works fine when powered up.I'm a little old school, having a preference for aard and igni. But they are quite useful.I got once a helpful bug on the quen spell. It stayed for 3 days, until I entered Vizima again. Very helpful in the swamp^^Didnt power up axii so it got a little useless in advanced game...
Aard is kickass ! Igni is too, but less 
Quen is good too, when I am fighting with group of monsters !
Quen is good too, when I am fighting with group of monsters !Igni is easily the best sign in the game. Put a couple of talents in it and you have a spell that not only deals direct fire damage, but also incinerates, frightens and puts in pain everyone around you.
Aard was very supportive when I first started the game on Hard, when later on Igni takes over as the first spell I would cast in combat due to it's muti- functions abilities, damage, Pain, Fear, if 5 or 6 enemies were changing at me, from one Igni, on average there are only 1 or 2 left for me to deal with at a time. Because of this, I have never needed to use Quen to buy time for me to buff and select the right blade.Two blasts of Igni take out all of those Mutant Assassins surrounds you at the end of the game of Normal difficulty - Example:http://uk.youtube.com/watch?v=ccDJ1--KNkYOn Greater Brother on Normal, I could do over 200 damage on each targets caught within Igni from the first blast, and further more damage from them being burnt.From chapter IV, Igni is responsible for about 70% of my damage output.I am sure you don't NEED Igni to play through the game, you can if you like; hack away, but I find Igni very helpfulAard at high level is still very good, but I am now playing on Hard, the enemies has a better Stun resist, making Aard less effective compare with Igni's Muti- Aid.Edit: Here is an example of using Igni to take out AJ (boss of chapter V), Igni is responsible for over 90% of the damage: at 4:00 http://uk.youtube.com/watch?v=4w5bx0pZF_s
I'm playing on normal, and lately I don't use the aard sign so much because it robbs me the delight of swordfight. Most monsters just die instantly...
: I tend to use Aard the most, upgraded with knockbacks and stun it's pretty easy to oneshot mobs. Quen is very nice (at later upgraded levels though) when you got loads of mobs that do melee damage, the shield will make them kill themselves and gives you the oppertunity to chuck a potion if you need it. Tend to use Igni allot too as the incinerate afterdot (damage over time) is nice in once again packs of mobs. don't rly use Yrden or Axii much though, heck only used Axii once so far on the end of chapter 2 (professor/Ajar ight)
axii instills fear on low levels, hex causes the enemy to become friendly, you can spend talents to increase the possibility of hex.igni is THE ROCKER, i tried to boost aard, igni, axii alone and soon dropped axiiwhen multiple opponents:- fight the nearest, let you surround you- switch to group style 1st combo, when finished, blast them with igni- commence group style: 6 enemies gone in 3 combos !!!!!igni is the master.so is the shield thing really useful ? i really just stopped boosting any other signs than igni and aard.how is the fear thing ? because it is limited to a certain point it doesn't sound good.
At this moment, I swear by Igni and Aard, but I think in the future patch, the game would be more interesting if they nerf Igni and Aard a bit, then pump up the other three Signs usefulness.They may want to remove Fear and Pain effects from Igni, and just let Axii purely responsible for status effect on enemies.Otherwise, there is not much point for Axii to be about.But may be they translate that from the Books of Sapkowski, otherwise surely they are aware of how wonderful Igni outshine from the rest.
has anybody played with a good developed shield power ? (the absorb thing)it should cause pain i think to enemies at higher levels. sounds also good for letting you get surrounded and then use some good group styles on them. i think on my next playthru i will go for group/strong only and leave fast stylein its early stages.