Riot's 133rd champion, Ivern, is what you'd imagine Maokai looking if he started hitting the gym. Despite Ivern having a root, a dash, and a three hit knock up, he'll be introducing some fresh mechanics and playstyles to the Rift.
WHAT TO KNOW
If you're playing Ivern you're going to have to be great at macro play. His passive, Friend of the Forest, enables Ivern to "tame" jungle camps. The passive doesn't force you to fight and kill the mobs, and doesn't even remove the bonus from Mobility Boots, but it does cost a bit of health and mana to start the channel. Once the spell is started the player can either smite to instantly claim the camp for the gold and experience, or be forced to wait around for the camp to become claimable.
At level 1 this takes some time, but it opens the door for new, adaptable jungle clears. If you're not interested in invading, starting at Krugs, moving to Raptors and then smiting Red seems like a decent enough clear. After clearing Red, don't forget to go back and claim your other camps. This start gives you a gankable amount of HP, and clears your red side jungle very quickly.
If you're feeling frisky, however, try and find the side the enemy jungler started. Once that happens, go to the opposite side of the map and start that buff, saving smite. Since Ivern doesn't need a leash he can start the Friend of the Forest channel on his own buff, trot into the enemy jungle and smite theirs. After claiming that, he can either head back to his original jungle side, or look to push his advantage somewhere else on the map.
Ivern also has a root, similar to Elise cocoon, as his Q ability. The Ability, aptly named Rootcaller, also gives Ivern and his allies a dash on auto-attacks. The dash places allies at their maximum attack range on the target, but, unfortunately for those with Vaynes on their team, won't dash them backwards.
The Green Father has a bit of a green thumb, too. His W, Brushmaker, does as one would think; it makes brushes. Ivern can carry up to 3 charges of bushes, and once placed, can change everything everyone knew about vision control on Summoner's Rift. Ivern also gets increased range and on-hit damage for his auto-attacks if he is in any brush.
Ivern's ultimate, Daisy!, is easy to figure out. Ivern summons a golem (think Tibbers without an AoE stun) that has a 3-hit knock-up on enemy champions. The knock-up doesn't effect only one champion, however, as it shoots a line through the targeted champion, somewhat similar to Braum's ultimate.
WHAT TO WATCH OUT FOR
If you're playing against Ivern there's a few basic things you need to pay attention to.
Firstly, expect early ganks. Ivern's don't have much to do while waiting for the Friend of the Forest passives to complete, so that leads to killing time. Good junglers always look to maximize the most out of their downtime, and since Ivern has a lot of that, expect more unique jungle routes and ganking patterns.
Next, Rootcaller has a surprisingly-long range. While it is a slow moving skillshot, don't just take for granted that you've outranged the ability. If you thought eating Elise's Cocoon was bad, imagine eating one where all your enemies get a free dash to you.
If you're middle lane, expect some cheese. As seen in the champion spotlight, Ivern can counter-jungle and gain level 2 even quicker than you can. With the long range and dash component of Rootcaller, he can reach you from over the wall at raptors, forcing your flash from what you may have thought was a safe-position.
Finally, controlling vision against an Ivern is a team effort. As long as they've swept the inside of either the Baron or Dragon pit, Ivern can wall off vision with Brushmaker. If you're team doesn't have a well-distributed amount of Blue and Yellow trinkets, you're going to be forced to face-check. If you don't face-check, Ivern and his team will claim the neutral objective for free.
Look to see Ivern as a Bard 2.0. He's the first, real "support jungler" (sorry Nunu) and introduces never-before-seen mechanics and abilities to the Rift. It might take low-elo a while to master him, but in the hands of a good jungler or well-coordinated team, Ivern could be one of the strongest champions to-date.