This animal begins to slowly heat up over the next four turns. After 1 turn the creature is invigorated and doubles its movement and rate of attack. After 2 turns the reptile is hot enough to cause cloth, brush, straw, or dry wood to burn and spread; heartier material or greener woods will smoke a lot. After 3 turns the creature sheds bright light for 100' and is hot enough to melt steel, allowing it an effective +1 AC against metal weapons and +3 to hit against opponents in metal armor...it will also boil any water near to the creature. Finally, after 4 turns, the creature explodes, sending molten chunks in a 300' radius - those not in cover need to save vs Breath/Burst or take 2d10 fire damage.
No aspect of this spell confers control or communication with the lizard. Casting this spell on a fire breathing dragon slowly heals them to their maximum HP and allows them to use their breath weapon at will for the duration of the spell's effect.