Overwhelming Splendor

If a creature enters the battlefield under enchanted player's control, any "when [this creature] enters the battlefield" abilities of that creature won't trigger. Any "as [this creature] enters the battlefield" or "[this creature] enters the battlefield with" abilities won't be applied.

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.

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities (such as equip and eternalize) are activated abilities and will have colons in their reminder text. Triggered abilities (starting with "when," "whenever," or "at") of noncreature permanents are unaffected by the last ability of 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.

Effects that modify a creature's power and/or toughness, such as the effect of Titanic Growth, will apply to the creatures no matter when they started to take effect. The same is true for any counters that change their power and/or toughness.

If a noncreature permanent becomes a creature, it will lose all abilities it has. However, if the effect that makes that permanent a creature grants it an ability, it will continue to have that ability. For example, the enchanted player's Riddleform will have flying once it becomes a creature.