Complex sentence: She had given him one dose of a contaminated chocolate bar two hours earlier in the day and promised him more chocolate if he met her in the conference room later; his arrival time planned perfectly as a demonstration for the witches to see how the formula works.
Split into simpler sentences: She had given him one dose of a contaminated chocolate bar two hours earlier in the day and promised him more chocolate if he met her in the conference room later. His arrival time planned perfectly as a demonstration for the witches to see how the formula works.