If you Smite it you get health back. If you deal the killing blow to it you get Crest of Cinders from it.

Using Smite on the Red Brambleback

Using Smite on the Red Brambleback will restore a large amount of health instantly (20% of your maximum health). This bonus can only be claimed once per spawn.

The Red Brambleback gives off green bubbles if the Smite bonus is available. Once the bonus is harvested, the effect disappears until the Red Brambleback respawns. This is only visible to champions with Smite.

Gaining health by smiting the Red Brambleback is... Read More

If you Smite it you get mana back. If you deal the killing blow to it you get Crest of the Ancient Golem from it.

Using Smite:
Using Smite upon the Blue Sentinel will restore a large amount of mana over 2 seconds (25% of your maximum mana). This bonus can only be claimed once per spawn.

Dealing the Killing Blow
This unit regens 25 flat mana regeneration per 5 seconds and 0.5% of their maximum mana (or energy) per second and has 10% cooldown reduction on their abilities. If slain, this buff transfers to the killer.

Gaining mana by smiting the Blue... Read More