first off I would like anybody who think trundle is a tank to smd, and secondly you need to know that the golem buff is EPIC for trundle, though this is not a jungling trundle guide.
I: items
]start with a dorans blade
get some baby boots when you have to B
BF sword
finish berserker boots
I usually go bloodthirster, though black cleaver is a good choice as well
save up for another bf sword and repeat this getting bloodthristers/black cleaver/infinity edge
get a youmuus if you see fit
if you need some tankyness/movespeed/slow go for trinity force after your first bloodthirster
if you REALLY need tankyness get a frozen mallet and maybe atmas
banshees veil if you need mr or are facing burst ap champs like veigar/ryze
final item setup would be something like:
berserker boots
bloodthirster
black cleaver
youmuus
trinity force
bloodthirster/infinity edge
or for some OFF-tank
zerker boots/merc treads
bloodthirster
black cleaver
trinity force
frozen mallet
atmas
against ap
merc treads
bloodthirster
black cleaver
youmuus
banshees veil
FoN/trinity force/infinity edge/phantom dancer
II: laning phase
when laning, just last hit and use bit to help with this (like when you mess up and leave a minion with barely any hp, or when the minion has barely too much hp to be last hit)
a bad lane combo for trundle includes 2 range with stuns, though this is only an early game problem. consider swapping lanes if this happens.
because you are heavy on AD and have contaminate which gives huge attack speed bonuses, you should have no problem taking down turrets, after the first one is gone, or after you pick up the bf sword, go snag the golem buff (trust me, you need it and your team wants you to have it if they want to win).
DO NOT use pillar/contaminate in the laning phase without the golem buff, you need that for biting minions (unless you can get a kill, which usually happens a couple times in the laning phase) or for defense if they are pushing hard on your tower
OK LET ME EXPLAIN THE BLUE BUFF FOR YOU:
trundle does need cdr, his abilities are pretty short cooldowns so this makes you a lot better being able to use these even more often.
secondly, and most importantly, your contaminate at level 5 gives you 60% attack speed, 40% movespeed and 40% cc reduction
implying that with infinite mana pool/cdr you should always contaminate and you FUCKINGFLY across the map. you will get so fed off minions/jungle and can always get to your team in time especially if you play smart. and always haveing contaminate up basically gives you a phantom dancer
sorry for the length but people have to understand that the blue buff is SO important for trundle, and no you dont want mana/cdr items. Those are taken by bf swords
III: important info on abilities:
I wish I had videos for this part but I dont so ill do the best I can explaining it
bite max first : gets FAT bonuses off AD and reduces their AD. Use this to last hit and take down anyone you want. Trust me, it hurts.
contaminate max second: gives attack speed,cc reduction, and move speed. use this to traverse the map and chase down/escape (for best results, espcially when jungling use contaminate and immediately bite, it will skip the end of the animation for contaminate and up your dps, even though just a little)
agony ult/max when you can: saps some life/armor/mres. decent harass/can K.O. champs with low life escaping into turret safety and can make you rather tanky for 6 seconds if used on a hardcore tank. Also great for when your team is coordinated enough to focus somebody
pillar of filth 1 pt at lvl 4 or 8, max last: AWESOME if you use it right. Here are some useful way to be effective with it:
1) block off/single out targets by putting it right behind someone, then contaminate and go bite/smash them to death 2) escaping, put a pillar right in front of them, then contaminate and you get away easily. A good trundle is HARD to chase down
3) blocking enemies from pursuing an ally. and yes you can do this from behind a wall, it has decent range and works well in the jungle. your team will love you if you use this well
4) scouting bushes. So you dont have wards and don't want to find out if theres a gank waiting in a bush? pillar that SHIT
5) this is hard but...you can actually completely trap somebody against a wall if you place your pillar just right, then proceed to faceroll them. put it basically on them when they are close to a wall, if the wall has the right curvature it might happen. Its a lot of luck but use walls and your pillars well and it will happen sometimes
best places to use pillar: by towers, in the jungle, gaurding yourself when you are getting blue/baron because it adds to your sight range and gives you some extra time. If you place a pillar right next to a tower on the side closest to a wall, you can block that space so they have to go around the tower only 1 way (can be useful, especially with singling out targets by towers when you want to dive)
masteries/runes
I usually go 21/0/9 picking up heavy offense and some mana regen with 1 in utility spec for that ever so important golem buff.
9/0/21 or 0/9/21 are also viable seeing as how mana/movespeed/cdr are useful and some extra trankyness can be good if you are offtanking
for runes I go health quints, flat or per lvl dont matter
armor pen marks
dodge or life per level seals
cdr glyphs
IV: reasoning/conclusion
AD...all AD because it stacks with bite and the huge attack speed bonus from contaminate making you super effective versus their team
I think trundles most appealing aspect is that he moves so fast you'll never miss a teamfight and you have great cc with your pillar while going beastmode when fighting on contaminate. Add in his ridiculous chasing/escaping capabilities (though trundle hardly runs) and this is a champ you will love playing
his above average life will allow you to not worry about stacking life, so build him like a glass cannon, unless you really are getting focused and then you just pick up a frozen mallet which they will not like