She started boots 3 pots. Her ganks were amazing. She had gap closer, and she did insane damage. Often saw her nuke too. + she was quite tanky. She did land her stun very often tho. Also, she used her spiders to tank minions I believe.
Elise jungle is pretty good. She clears fast and has sick ganks. Once you get spectral wraith you can just sit in spider form all day with full HP and mana.
She's not a typical madred's/unupgraded spirit stone -> locket/aegis support tank jungler like Vi/XZ/J4/Volibear, but I personally think the only reason why you don't see more elise jungle is that elise top is sick too.