King's Tribute allows Trundle to jungle effectively as well as keep a sustained presence in lane.
King's Tribute has a range of 1000 and allows Trundle to heal from enemy minion waves as they die even if you can't last-hit them.
The heal from King's Tribute also helps in a team fight. As enemies around Trundle die, he is healed. Although the heal per enemy is not that much, it does stack up nicely.
Chomp resets the attack timer. Learn to bite right after you attack for a double hit. Remember that it also has a slight range and can be used to lunge towards an enemy if they are outside of his autoattack range.
Chomp is good for lowering the physical damage of enemies; try to focus it on enemy physical damage dealers. When facing multiple melee enemies you may want to bite each one every 8 seconds to keep the AD debuff active.
Trundle excels at fighting within his Frozen Domain . Try to draw enemies onto it.
If you are having trouble escaping or chasing champions, Frozen Domain gives you bonus movement speed so you can drop it out in front to help chase fleeing enemies or speed your escape.
Since Frozen Domain has a wide radius and fairly short cooldown, you can use the movement speed it grants to move quickly from pack to pack in the jungle by dropping it in the proper location.
Spamming Frozen Domain will allow you to reach your destination much faster but know that Trundle has a very limited mana pool and spamming will surely deplete it.
Frozen Domain should always be used when attacking a tower for the attack speed increase. Place it so that most of the affected area is behind you so that you can quickly run away from an approaching champion.
Pillar of Ice may not be big enough to block off a lane or a passage in the jungle, but if used effectively, a Trundle can make other champions have to walk around it in order to get to you, giving Trundle time to escape or to chase.
A good tactic to keep people on Frozen Domain is to plant a Pillar of Ice on the escaping champion which will then push them backwards if placed correctly, allowing Trundle to get in range to attack.
Pillar of Ice has a large sight radius and is very effective to check the brush and slow any potential sneaky gankers.
Pillar of Ice can be used defensively or offensively near towers. Defensively, underneath your own tower, place the pillar slightly away from your tower when it is being attacked. The enemy will have to brave the slow, a Chomp, and possible tower shot (if they retaliate), just to hit your tower. Offensively, underneath an enemy tower, place the pillar next to their tower when attacking it and they will have trouble chasing you away without being slowed. Be careful when using this under an enemy tower, because it draws turret aggro when an enemy champion touches it.
Dropping Trundle'sPillar of Ice to separate the enemy team offers some of the best counter initiation as well as initiation in the game. If you find an enemy out of position, a well placed Pillar of Ice can block off his or her escape, if somehow that enemy doesn't have Flash, as well as keeping enemy reinforcements from entering the battle. Understanding when to use Pillar of Ice for either purpose is important, as once it's gone, it's gone forever. Pillar of Ice can also save a teammate from focus by preventing enemies from crossing the terrain or once an enemy has initiated on a teammate, Pillar of Ice can block reinforcements from entering battle for a while, giving your team a little 5 on 1 quiet time with the initiator alone. Combining this tactic with Trundle'sSubjugate can quickly dispatch an enemy, making the team fight effectively a 5 v 4.
Because enemies usually haven't built much armor or magic resistance early in the game, Trundle'sSubjugate does not offer him much survivability. Its main use early is for the magic damage, the additional health, and for lowering the enemy's resistances to make Trundle hurt a little more (and Trundle's teammates if they attack the correct enemy).
Use Subjugate to soften a powerful enemy tank for your own survivability or to create a target for your team to focus fire. Sometimes, it may be better to Subjugate a squishy target as once they die, Trundle will be healed by King's Tribute.
When a early team fight breaks out, use Subjugate on the squishiest targets, like whomever is doing more damage between the ranged attack damage carry or ability power carry.
Trundle'sSubjugate enables him to effectively become a tanky DPS even without building many tank items. This combined with inherent CC reduction makes for a DPS champion that is difficult to disable.
Although Trundle has an exceptional early game, he does not scale well. Beginning around mid and into late game, Trundle becomes very item dependent to increase his survivability and damage. Building good and cost effective items are important for him.
Damage
An early Wriggle's Lantern helps Trundle whether in lane or the jungle. The minion damage proc helps his farming, the life steal gives him even more sustain with King's Tribute, and the armor strengthens his anti-AD role with Chomp as well as alleviating his armor scaling problem.
Blade of the Ruined King is preferred over The Bloodthirster; Trundle becomes an effective anti-tank in conjunction with Subjugate and TBT is not very consistent as its item efficiency depends on maintain stacks.
Youmuu's Ghostblade is good for Trundle as it gives a lot of stats that will help him perform well. Cooldown reduction is good because Trundle is only as good as his buffs and debuffs last and helps him keep them up. Attack damage, critical strike, and armor penetration help him do more physical damage and furthermore, armor penetration helps even more combined with Subjugate. The active will increase his attack speed and damage per second.
Chomp works especially well with Sheen and Trinity Force as it will both activate and consume the proc to deal increased damage. This can allow Trundle to last hit minions more effectively and take down targets easily.
It should be noted however that Trundle is very much reliant on specific jungling masteries and runes in order to support that style of play. Jungle should only be taken if conditions are favorable.
Jungling order: Wolves → Blue Golem (Smite) → Wraiths → Wolves → Red Lizard (Smite) → Golems → Gank*
Trundle's strengths in the jungle are his sustain with King's Tribute and his ability to invade the enemy jungle as he can duel most AD champions favorably with his Chomp and he easily escape with Frozen Domain and Pillar of Ice.
Trundle can gank at level 2 (really just showing his face to make them waste Flash) but he needs all of his abilities (Frozen Domain and Pillar of Ice are critical so level 3 at the earliest) in order to gank effectively so he is pretty much stuck in his jungle route, no shortcuts should be taken.
Avoid battling Trundle near minions. If a minion is killed, Trundle will regain health due to his King's Tribute. This can sometimes turn a battle to his favor. Be aware that he has exceptional health regeneration along with his King's Tribute to easily sustain himself and recover from most harass in a laning situation.
Trundle excels at fighting inside his Frozen Domain AoE. Moving away from the spell's AoE can help you 1v1 him.
Pillar of Ice can block your way of escape and slow your movement speed. Therefore, it is best to avoid the spell's AoE or use Flash to quickly go over it.
Sources of easily repeated slows, such as Frost Shot or Frozen Mallet, largely ignore the CC reduction aspect of Frozen Domain, as the ability reduces the duration of their slows, not the effectiveness.
Knockbacks/knock-ups are not affected by Frozen Domain. Having them available is the next best way to kite Trundle.
Top laners with ranged capacity (such as Jayce or Kayle) will have good effect against Trundle if he attempts to push or attack.
Avoid a head-on fight with Trundle early-game in most cases. His early-game damage is high, and his Chomp can reduce your own ability to retaliate. Try to focus on ranged harass and wearing him down as Trundle has fewer options to retaliate than he would against melee attackers.
If Trundle uses his Subjugate on you, it is best to avoid him and wait until the debuff is over because Subjugate can melt even the toughest tank, or allow Trundle to dive into your team and survive strictly attacking your squishy damage-dealers with the rest of his team helping him even with your best attempts to focus him down. As it is a large part of Trundle's durability which is necessary for him functioning in teamfights, using escapes to avoid letting him take advantage of Subjugate's bonuses can leave him much more vulnerable while it is cooling down.