as a rammus jungler.... (for those games where i don't get mid lane >.>)
-> ninja tabi / merc treds / mobi boots in that preferential order, where i reserve merc treds for cc heavy teams, and mobi's for "wow the enemy team is super pushing, let me go ahead and just repeatedly gank lanes"
second item has variation, but i will strongly consider warmogs/thornmail/righteous glory/
-> RG for more ganks, thornmail against those whopper AD only teams, and warmogs for a general balanced team.
warmogs actually procs at this time, i will have 3k hp with it.
-> then go thornmail or warmogs for sure. (which ever one i didn't buy) ((but if i choose to build RG as the second item, then i will go thornmail next for the armor)
-> CDR items
are you're two main choices. i look to see whos doing the best, whether it be the enemy mid laner.. ill pick up a locket, if its the enemy ADC, ill consider frozen heart.
-> example full build
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some might argue "why only one armor item, you're not using your passive"
good question, this is a generic rammus build, (+120 armor from DBC is quite a bit, and offers just over 70% damage reduction for both types) if im truly looking to counter a full AD enemy team i will build
->
->
<- switch warmogs/TM as needed ->
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^ offers 4k hp, and more than enough armor for those "i hope you've built a last whisper by now" moments.
the biggest concerns as jungle rammus, is that your team is pushing, and you're being invaded on.
you can mitigate invasions by warding your jungle entrances so you can react and potentially kill invaders.
but if you cant get early game ganks off theres no real reason to have rammus other than "im going to flash on top of your enemy adc in the late game"
rammus naturally has very slow clears, thats his weakness, so someone with devourer on the enemy team who is going ham and farming, will have a gold lead over you and will likely have more of an impact later on.
what people tend to forget that is rammus can towerdive sooner than most tank junglers thanks to his W, and rushed health pool.