Overwhelming Splendor

While the enchanted player can still activate mana abilities and loyalty abilities, creatures that player controls won't normally have any of those abilities to be activated.

An activated mana ability is one that produces mana as it resolves, not one that costs mana to activate. A loyalty ability is an ability of a planeswalker whose cost specifies how many loyalty counters to give or remove.

If Overwhelming Splendor leaves the battlefield at the same time as a creature enchanted player controls, any "when [this creature] [dies or leaves the battlefield]" abilities of that creature won't trigger.