Reward 1: Significantly more likely to find whales/chasm conchs
Reward 2: character keeps combat discoveries after death
Reward 3: Don't care
Reward 4: Don't care
Reward 5: Flex emote, to flex on nabs
Example quests, all would require you do 100% damage, nobody else aggros the beast, and the beast not lose aggro on you after taking damage:
Kill a cave angler with no items equipped without touching land
Kill 8 cave louse in a single attack
Kill 5 bears in a single attack
Kill 5 nidbanes in a single attack
Kill (last hit) 10 bears within 10 seconds
Kill a mammoth without it using trunk gunk
Kill (last hit) 3 mammoths so within 10 seconds of each other
Kill a mammoth only by throwing spears, without a horse
Kill a chasm conch without it using trunk gunk
Kill a whale without leaving the deep ocean
Kill a whale while standing on a Kelp Island (after object control object)
Kill a whale while swimming at least 500 tiles from land/walkable surface
Kill a beaver king/ant queen while having 0 AC from when the door opens until it dies
Kill a bat queen without taking hard health damage
Kill a troll using a spear(melee), without letting it use a single move
Kill a level X or lower troll without taking hard health damage
Kill a level 9 troll