You don’t have to activate “3-Hump Lacooda”’s effect just because you have 3 copies in play.
You can choose which of the “3-Hump Lacoodas”’ effects you are activating; it can be one of the ones you are Tributing or the one that is remaining on the field.
Tributing 2 “3-Hump Lacoodas” is a cost.
If your opponent chains “Ring of Destruction” or “Book of Moon” to the activation of “3-Hump Lacooda”’s effect, the effect is not negated.
If you Summon your third “3-Hump Lacooda”, you can activate its effect before your opponent activates “Torrential Tribute”.