True Summoning

You call upon your arcane knowledge, grasping at the threads of reality as you feel their light and unfathomable depth trace and loop around your fingers. With a concerted effort of intellect and will, you speak the name of a celestial, fiend, or fey as you reach forth into the void, and offer an outstretched hand of friendship. Hearing your plea, the creature is called into your realm, and regards you as a friend. The creature is true to its alignment, and will regard you and its surroundings accordingly. The creature acts on its own initiative in combat with full access to its abilities per its creature/monster entry, including AC, HP, and resistances. 

In order to summon a creature, you must have spent a minimum of a month's time studying it in your tomes; conjuring being of flesh and bone into our realm is a task of masters, and masters alone. Additionally, the summoned creature's challenge level cannot exceed that of the spellcaster.

Once summoned, the creature now "knows" you and tells you its true name if asked, allowing you to recast the spell as instantaneous in the future if you try to summon the specific creature again. If the creature's hit points are reduced to zero, it is killed outright, and cannot be re-summoned.

Your actions while in the presence of the summoned being are judged by them relative to their alignment; should you act not in accordance with the creature’s alignment, you must perform (at the DM’s request) a DC 20 persuasion check. On a failure, the creature returns to their home-plane, and will tell others of your actions. Furthermore, forcing the creature to perform a task that is severely at odds with its alignment will result in your bond being "desecrated". Make a DC 27 arcana check, if failed the creature returns to the void and cannot be re-summoned. Failing by 10 or more results in you being disowned by the plane of the creature's origin: you may no longer summon any creatures who call this plane its home.