Main Attribute: Intelligence  
Role: Carry, Nuker, Initiator, Escape
 
Lore:  
Throughout history, there only existed four ponies with the title of a Grand Magus; Aghanim the Magnificent, Rubick the Cunning, Twilight Sparkle, and the most famous of all, Starswirl the Bearded. A Grand Magus with a twist, Starswirl didn’t achieve the rank by the same path of the others, for he never understood the magics that came from friendship - which is peculiarly, a foreign concept to him. Hence the Legendary Starswirl never learned the many independent spells his predecessor and succesor mastered.
 
Instead, what gave Starswirl his notoriety and an unanimous title as the most powerful unicorn in history of Equestria is his “invocations.” His most powerful ability, which he gain from his deep insights, knowledge and mastery in harnessing the power of Wex, the lightning, Quas, the ice, and Exort, the fire. By combining and manipulating them using the power of will alone. Starswirl is able to perform magic unlike his peers, and of a level so great that nopony would dare incur his wrath. One can only imagine what kind of feats Starswirl could pull off, if only he understands the magic of friendship.
 
In a different twist of fate, Starswirl mysteriously vanished without a trace from history after an attempt to invoke his most powerful invocation yet - the infamous longevity spell “Sempiternal Cantrap.” Rumour has it that Starswirl is still among us, but those who claimed to have crossed his path testified that his motivations are hazy.
 
P.S.  
As Star Swirl’s design is not known at this point of time, his form here is based on the drawing “Legends of Equestria” at this [link]
 
[link] for the real Invoker (whose real name is actually Carl)