|I couldn't find Abraham Lincoln and a pony, so have Twilight Sparkle with a beard instead.|
Unfortunately for you, Trixie has decided to cut off access to her Equestria Portal spell to anyone labeled as a "brony" or fan of the show "Friendship is Magic". Something about creepy humans taking pictures and asking for autographs was the cause, she didn't elaborate.
She is still happy to allow scientific exploration though, and is willing to summon a historical figure of your choice to analyze Equestria and report back with their findings. And because Trixie needs to show off her great and powerfulness, the historical figure cannot be currently alive! She wants to impress the world by bringing someone back from the dead.
So there you have it! Choose any historical earth figure and send them off to Equestria. It can be anyone from Genghis Khan to Leonardo da Vinci How do you think they will react?