The Destined White Mage

Each creature with lifelink dealing combat damage causes a separate life-gaining event. For example, if two creatures you control with lifelink deal combat damage at the same time, The Destined White Mage's third ability will trigger twice. However, if a single creature you control with lifelink deals combat damage to multiple creatures, players, planeswalkers, and/or battles at the same time (perhaps because it has trample or was blocked by more than one creature), the ability will trigger only once.

Some cards refer to you having a "full party." This is true if the number of creatures in your party is four.

If you gain an amount of life "for each" of something or "equal to the number" of something, that life is gained as one event and The Destined White Mage's third ability triggers only once.