I'm a huge fan of Air Elementals.  In the early/midgame, they are rather powerful and fast, and can usually survive a hit or two.  So, yeah, I'm all about the summoning tree.  Plus the Air Elemental's impale ability is a nice way to whittle down the enemy stack a bit.  Their high movement rate is also nice when making a 'fast response' stack (i.e. a stack that moves 4 or 5 instead of 2).

Ice Elementals are also nice, mainly because of their 'slow' effect when they strike in combat.  Plus, they can generally survive a hit or two in the early/midgame assuming they aren't in a swarm situation or facing some epic creature.

The only 'disappointment' is the Familiar, which becomes available via the tech tree.  Too few hit points to risk in combat, and although they can also summon creatures, they are generally of lower level.  Summoned creatures are nice cannon fodder though, if you have the mana to spare.  They don't tie up city production when replacing them...

Finally, if you summon a creature during tactical combat, this can improve your odds in a fight, if your stack was full to begin with; summoning creatures in combat can exceed your stack size.  Of course, the creature goes bye bye at the end of combat should it survive, but if your stack was full to begin with, this isn't as big of an issue.

Summoning is decent if you go the earth elemental route but any good summoner is worthless at everything else due to the huge Trait point cost.

The reason no summoning champions exist is for the same reason, it requires so many traits to do that no champion could ever be worth it, only a pure summoning Sov is good enough.

Also the random and limited summons really really bother me. Every Summoner is the same due to the horrible trait tree that forces you to pick ice then air, ect ect. Summoning needs to be affected by your general elemental traits and cost less traits. Also more diverse and interesting traits like allowing 2 of the same summon or an upgrade to summon a group of 3 instead of just 1 ice elemental late game.

The Summoner tree is great, but I wouldn't take the Summoner trait.  

The Shadow Warg is only good very early game, and +2 levels to summons just aren't that great.  It's certainly a much better trait in LH than it was in FE, what with getting the ability to summon things being an uncertainty in FE.  Still, I don't feel like there's a significant enough bonus.  +4 HP, +2 accuracy, +2 spell resist, and... that's about it.  Even when summoning a Skeleton Horde (which gives you 9 skeletons) I see little benefit to it.

Maybe it's not worth it on lower difficulties, but I play on insane/insane, and it's very good there.

Overall I like playing as a summoner.  I agree the summoner trait is kind of weak though; +2 levels for many summonses is just 6-10 extra hp.  Some summonses like the whisp, increase their healing with level.  So i'm kinda reserving judgement as to its benefit at higher levels, since I ended up beating the game as a summoner on expert at lvl 9 (air was the farthest I had seen).

Anyways, here's some tips I picked up for getting the most out of the summoner.

The Pricipone's crown is essential for summoner.  Lets you sustain your "strategic" summons without manna cost.  

Your alignment (dark or light) affects which summonses  you get.  For instance, light gets whisp and light bringer, whereas evil gets skeleton and skeleton hoarde in their place.  Not sure if those are the only differences.  Haven't played evil, but I think they are missing out.

Mage tree pets can be cast anywhere on the battlefield.  If your hero has high initiative you can lock down about 4 enemy units fairly easy, just cast a tank summon in melee range, and they'll be stuck attacking that summons.

There's a spell (unit enchantment) you can find called summoner's boon, which increases the attack of all your summonses by 50%. 

If you make familiars, your familiars can summon anything you can.  If you really like lightbringer's u can make an army of them by making familiars to cast them.  They are a strategic spell so you can cast it out of combat.

Shadow worg is useful for creeping early.  Lets you send waves of wargs at mites, wolves, spiders, bear armies to soften them up for your sovereign's army to get exp.  You just weaken them, then come in with your army.

Later you can send lightbringers (light faction only) at much more powerful armies to soften them up.  Great tanks.  50% phys. dmg reduction.  Plus they get two area effect blind spells that stack (on summon and on cast).  Used them to tank everything, even juggernauts and such (with support from a whisp).  

Whisp (light faction only) is good sustained healing.  Healing scales with its level.   Good combo with lightbringer.

Frost - Didn't like that much.  He "slows" everything he hits.  Slow just isn't that powerful imo.  He's no tank, but does elemental damage so he can hurt most anything he hits.  

Air - got too late to evalute.  Didn't look too promising though.

+100000 what heavenfal said

+ 1 Karma

Must say I've been positively impressed by a default Procipinee investing perks in the mage class (obviously) and then pure summons - down to lightbringer and then onwards on the line to earth and grave elementals, only picking up a single non-summon perk (knowledge) as the first perk after getting the lightbringer. Those +2 levels on top of the perk level boosts and (eventually) shard boosts really add up, giving you a very powerful army compared to what the AI fields all the way until the endgame - and if you lose a unit, you can just resummon it immediately.

There's no room for magic development there, though if you get some air champions you can level them up a bit and eat their souls to boost your magic should you so desire for teleportation, and it does mean enchanting Procipinee with every enchantment known to man to boost her combat prowess and spending most of the time either whacking monsters in melee (for the swarm bonus) or casting haste and slow, but it works, and there's a sweet spot in the midgame where your one army with summons will trump anything the AI fields.

(And, of course, when it works with a default leader, I'm sure it works even better with a custom summoner, so long as he gets her headband.)

It is a bit of a one-trick pony act, though, going the dedicated summoner route, and I'm not sure how it would work out for the empire faction. That whisp+lightbringer combination is so very, very, powerful, and using the wisp tactically to heal multiple summons at the same time every 5 rounds is an important part of the empire summoner tactics.

Let's just say that the "no XP without combat makes using a hero as administrator pretty much meaningless except for the base unrest reduction" and "25% chance for 1XP/turn for heroes in the faction specific adventurers guild is pretty much irrelevant given the xp requirements to gain levels" remain as relevant and fundamental flaws in Legendary Heroes as they were in Fallen Enchantress, and that combined with "XP in combat is shared between heroes", most heroes are destined to spend most of their drab, wretched, lives as lowlevel -5% unrest reducers OR being sacrificed so the sovereign can steal a spell level.

The game mechanics of leveling heroes and hero utility just don't mesh all that well.

Actually it is the opposite. Summoner is very strong in early game and it is viable choice for insane/insane game. Do you need better recommendation than that ? Please keep in mind that wisp and lightbringer are (at the moment) superior to skeletons.

To really make a summoner worthwhile, maybe allowing X summons per X related mana would allow more significance to summoners in late game, especially on a large map. That or include boosts in the magic tech trees, to be unlocked at varied time as game progresses.