Olloch the Glutton

At the beginning of your precombat main phase, you may sacrifice a creature. If you do, put X +1/+1 counters on Olloch the Glutton, where X is the sacrificed creature's power.
At the beginning of your end step, if a creature left exile since your last end step, transform Olloch the Glutton, and put a number of digestion counters on this card equal to the number of +1/+1 counters on Olloch the Glutton as it transformed.
(Transforms from Do Not Feed The Frog)