Conjurer

A conjurer is a Mage specialized in Conjuration school, focusing in summoning and creating things.

Unfortunately this does not exist in DDO, but a way to emulate it if you wish to play such a Mage for Role Playing reasons is to chose a sorcerer and only select conjuration spells. If you were to do that then the following feats and enhancements would be beneficial.

Usefulness of different feats
Quicken Spell could be a lifesaver when faster summoning is needed.

Benefit of a Sorcerer
A sorcerer already has faster casting that affects his summoning speed significantly compared to a wizard.

Usefulness of different attributes
As with all spell casters, the respective caster attribute is most important (Int for wizards and Cha for sorcerers). For a conjurer, Con is the 2nd most important attribute because it bumps up concentration, not to mention it adds more HP as a cushion when you are getting hit. The reason for this is that summoning takes time and if you are getting hit in battle, you need to be able to concentrate so you don't get interrupted before you get the creature you are trying to summon.

Usefulness of different Sorcerer enhancements
Energy of the Dragonblooded is useful for every sorcerer.