2

While moving through a river a few faintly glowing leeches attach themselves  but it's not blood they're draining but magic itself.  (DC 15 Perception to notice them  for each tile traveled while un-noticed 1 spell slot will be 'drained')

3

A thick curtain of vines hangs before you blocking the path. If looking carefully small jungle creatures can be seen entwined. When cut the vines quickly strike like snakes trying to ensnare the party.

4

A group of creatures lay bloodied and scattered around the base of a tree  a different group of creatures are mocking the survivors who have climbed the tree to survive.

5

The party comes across a long forgotten cache of weapons. Most of the mundane weapons have long rusted  but a single weapon lies at the bottom of the cache looks brand new. Maybe a magic item? Cursed?

6

A dim-witted troll named Gnasher is attempting to save his pet boar named Snouts from being eaten by a large carnivorous dinosaur. If they help the troll save his pet he can lead them to one of the hidden locations in Chult.

7

Grung Slavers - A group of Grung are out searching for captives. They have laid an ambush along the trail and burst forth with croaks and squeaks
2x Grung Elite Warrior | 1x Grung Boss
(Loot: Feathered Headdress worth 100 gp, Citrine Necklace worth 100gp, 2 Citrine Bracers with 100 gp each, 4 Bloodstone rings worth 50 gp each, 16 +1 Arrows)

8

Hanging from one bound ankle an irate Noble dressed in the finest (and mostly useless) expedition gear money can buy swings before you.

9

A buzzing hive can be seen hanging low in a tree inside contains a honey so delicious it's almost addictive. WIS15 save to resist the temptation to harvest the whole hive. If the hive is harvested a group of giant insects will attack.

10

Plump white fruit hang from a tree overhead giving off a sweet and spicy aroma  biting into it lets the thousands of tiny spiders free. DC10 WIS save or gain 1 long term madness trait.

11

A pool of bubbling tar is in front of you. You see an animal go in and screech in pain  then silence. Suddenly  the creature's skeleton covered in tar struts out and into the jungle as if nothing happened.

12

A tribal dragonborn lays slumped against a tree holding his eviscerated abdomen  in a rasping grunt he says in draconic "opened  by bahamuts breath they opened them all!"