Drogskol Reaver

If Drogskol Reaver deals enough first-strike damage to destroy each creature it's blocking or was blocked by, it won't deal any damage during the regular combat damage step and its last ability won't trigger a second time that combat. This is different if Drogskol Reaver is attacking and somehow gains trample.

Drogskol Reaver's last ability triggers just once for each life-gaining event, whether it's 1 life from Dazzling Angel or 4 life from Apothecary Stomper.

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, Drogskol Reaver's last 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.