Each entity, when summoned correctly, did in fact appear:
1) The Blob appeared as a goblet full of some kind of gelatinous substance;
2) Mary Shelley appeared as a woman with a wand;
3) Sigmund Freud appeared as a bearded man with a sword (sometimes a sword is just a sword); and
4) Jeanne Dixon appeared as a woman wearing a pentacle pendant.
When the last summoning was complete, all four entities then appeared simultaneously, and delivered the Endgame Logic Puzzle. When this was solved, the resulting set of instructions led the solving team to 6-233 (the Amdur Room).
At the front of this room, there was a projection screen with a puzzle taped to it, involving the selection and arrangement of certain letters from the four incantations. The resulting message was THE SCREEN IS A RED HERRING. When the solvers raised the screen, this revealed five tarot cards, at various heights and in various orientations, each with either a plus or minus sign and a number on it.
The meaning behind these cards remained mysterious until the solvers made a further discovery: When a curtain on one side of the room was moved aside, it revealed (a) the screaming ghost of Agatha Winchester, and (b) more tarot cards. Other tarot cards were hidden in other locations, at wildly varying heights, all around the room; there were 43 in all.
Each tarot card specified a letter, as follows:
1) The entity for each phase of the Hunt, when summoned, appeared with an item corresponding to a tarot suit (The Blob was in a cup, Mary Shelley carried a wand, Sigmund Freud carried a sword, and Jeanne Dixon wore a pentacle); the suit of the tarot card thus specified one of the four phases.
2) Each phase had twelve regular puzzle answers, and each phase's metapuzzle required that these answers be assembled in some specific order (see the individual metapuzzle solutions for details). A tarot card of rank m (counting "page" as 11 and "knight" as 12) specified the mth solution word in the phase from (1), in the order used for that phase's metapuzzle (not the order in which the puzzles were originally presented).
3) Each regular puzzle had an associated numerical "Spookiness Rating." This rating, when added to or subtracted from as specified on the tarot card, yielded some number n; the letter indicated by the card was then the nth letter of the word from (2).
The sequence of 43 letters obtained in this manner formed the directions to the bloodstone, thus ending the Hunt.