Why most supports should take thunderlords
This was originally going to be a comment in reply to someone elses post, but after I wrote up a 2 page essay I decided it would be better to just make it a post of my own.
basically there are 3 kinds of supports. tank support, poke support, and sustain support. of course, some champs fill multiple roles but thats a matter of preference. Regardless all supports have varying degrees of cc, and tools to defend their carry.
1: there isnt really a good enough tank support mastery. the 6% damage reduction mastery is negligible(if your ally takes 1000 damage, you reduce that by 60 damage which is basically nothing/less efficient than the other picks.) and the other 2 final tier tank masteries are inherently selfish picks.
2: sustain supports have a mastery in the the utility tree which boosts heals/shields by 10% and give bonus armor/mr to the target on heal/shield. The problem is that basically every sustain support except soraka and taric doubles as a poke support which leads to
3: thunderlords. unless you're very focused on sustaining your ally/bodyblocking skillshots for them, thunderlords is the optimal mastery. it is balanced so most of the damage is based on per level scaling which basically gives you a chunk of free damage, and you don't need to spend money to scale the damage into usefulness. doing the math:
the tank mastery reduces damage by ~40-80 depending on level before your carry dies. It only benefits the nearest ally, so the really negligible damage mitigation is really not very good for much of anything.
if you heal for 200 with the sustain mastery, you give an extra 20 healing, and give 5-22 armor/mr based on level. overall you might save your ally about 80-100 hp in an extended fight, and that's being generous toward the armor/mr buff. The other problem is that the efficiency of this depends on when you use it. in order to get much out of this mastery, you would have to heal someone right when they first get damaged so the resistances have the maximum time to mitigate damage. the problem is most people reserve heals for when someone gets below 25-50% hp which means it has very little opportunity to function. it's also not beneficial for trades since if you heal someone after the trade you might get a bonus of 10-30 hp(most champions don't get much above 300 healing strength without massive investment into ap at which point you really should take thunderlords to maximize your ap), but the resistance bonus completely goes to waste. Shields benefit more, as they can be used more freely such as at the beginning of fights, and are allowed more strength than heals. Ultimately shields are the only place this mastery shines which basically means janna and karma are pretty much the only supports who can take much advantage of it. fitting since the actual picture on the mastery looks like janna. The fringe support who really benefits from this is shen since his q healing will resistance buff anyone who hits the target.
As far as thunderlords, the damage bonus may not seem like much on paper aka 100 at level 10, but the key here is gold efficiency, and poke. if you can consistently get 3 hits off, you can add a decent chunk of damage without spending any gold. since supports basically have no spare gold to spend on selfish items until well past lane phase the bonus damage from thunderlords is hugely economical for them. The benefits extend beyond that though: killing an enemy faster means they have less damage output. That's situational and hard to measure, but if you kill an adc 1 auto faster(a reasonable possibility given the numbers), you just saved someone ~60 hp in early game. Even if you don't kill them, forcing them to retreat earlier will have the same effect. as carries get more powerful, that number gets ever higher which means the more powerful your enemy is the more valuable this mastery is if your team does get a kill. More than that, if you're a support who builds any ap this mastery makes your purchases more gold efficient, and supports need any kind of gold efficiency they can get. additionally, this is very beneficial for trades especially in the early game. 70% of the time, the enemy adc likely has the crit mastery, and get's very little advantage from it until mid-late game. since your mastery will proc, while theirs wont, you have a decent advantage when trading. 50-100 damage one way or another can make all the difference there. Finally, many supports are based around high cc combos which give them the opportunity to take good advantage of this mastery.
