At the moment Summons in game are substantially underperforming and I think there are a few changes that may help with that (not including any AI fixes).
I dont think they need a huge power boost in heroics they are just punishing to use if they die so for starters:
1. Remove all death penalty for using summons/companions/hires as in exp/hp/sp hits because they died.
2. Change the 1/rest Raise dead on your companion to a 1 min cooldown.
Next the power of the summons is pretty lacking end game but to balance just giving streight power creep, I suggest revamping the feats so a player has to choose between personal power or summon power for example:
(Feats replace each other and do NOT stack)
Augment Summoning: (ML: 0)
Your summoned creatures, charmed minions, and hirelings have +4 to all ability scores, increased health (5 hp per character level), and increased fortification (+50%).
They also get increased Melee power, Ranged power, Universal spell power, PRR and MRR equal to (3+ 1/3 your INT/WIS/CHA modifier + conjuration bonuses).
They also get 10% Enhancement bonus to move speed.
Improved Augment Summoning: (ML: 10, Requires: Augment Summoning)
Your summoned creatures, charmed minions, and hirelings have +8 to all ability scores, increased health (10 hp per character level), and increased fortification (+100%).
They also get increased Melee power, Ranged power, Universal spell power, PRR and MRR equal to (6+ 1/2 your INT/WIS/CHA modifier + conjuration bonuses).
They also get 20% Enhancement bonus to move speed and get 20% concealment (Blurry).
Greater Augment Summoning: (ML:20, Requires: Improved Augment Summoning) (Epic Feat)
Your summoned creatures, charmed minions, and hirelings have +12 to all ability scores, increased health (15 hp per character level), and increased fortification (+150%).
They also get increased Melee power, Ranged power, Universal spell power, PRR and MRR equal to (10+ your INT/WIS/CHA modifier + conjuration bonuses).
They also get 30% Enhancement bonus to move speed and get 25% concealment (Lesser Displacement) and 10% feat bonus to dodge.
Perfect Augment Summoning: (ML: 30, Requires: Greater Augment Summoning) (Legendary Feat)
Your summoned creatures, charmed minions, and hirelings have +16 to all ability scores, increased health (20 hp per character level), and increased fortification (+200%).
They also get increased Melee power, Ranged power, Universal spell power, PRR and MRR equal to 2x (10+ your INT/WIS/CHA modifier + conjuration bonuses).
They also get 40% Enhancement bonus to move speed and get 50% concealment (Displacement) and 10% feat bonus to dodge, Ghostly 10% and 10% feat bonus to attack speed.
These feats would replace "Augment Summoning", "Improved Augment Summoning" and "Scion of Elysium", all other summoning buffs would stack with this feat chain (Epic Summons, Grand Summoner, Past Life: Druid etc.)
Thoughts?