Assassin Masteries: Why Thunderlord's Decree is better than Deathfire Touch.

This is strictly an assassin mastery. It is absolutely gorgeous on champions that have multiple instances of damage on spells (LeBlanc's Sigil of Malice, for example), as it proc's on each moment of damage for these spells. In the case of LeBlanc, she can do her simple Q+W combo, and proc it, providing a beautiful damage boost no matter the level. It is an excellent trade tool for assassins, as well as a boon to their burst damage output. Now, as to what you are missing by going for this keystone: as you can have a 12/18/0 versus an 18/12/0, the only masteries you are missing out on are the last two tiers of the Ferocity Tree. As an AP Assassin, like LeBlanc, you would invest your Magic Penetration into Piercing Thoughts. Now, if you are up against a champion that likes Magic Resist, like Galio, this is probably a better move, as the higher Magic Resist means that you are ignoring more due to the percent ignore. However, for most carry champions, your primary targets as an assassin, you will more than likely not go up against anyone with more than the base 30 Magic Resist, or with flat Magic Resist glyphs to put them up to 42 Magic Resist maximum. Now, the max percent Magic Penetration off of Piercing Thoughts is 7%, so, when you take into consideration the enemy's Magic Resist, that is 2.1 Magic Penetration for 30 Magic Resist and 2.94 for 42 Magic Resist. Compare these numbers to the Cunning Mastery Precision. At full mastery rank, at champion level 1, this mastery provides 3.3 Magic Penetration regardless of the enemy's Magic Resist, and at level 18, this total reaches a total of 8.4 Magic Penetration, a total that the enemy would need to have 120 Magic Resist for Piercing Thoughts to equal. Therefore, unless you are fighting a team of tanks and bruisers that build 50+ Magic Resist per champion, Precision is always going to outstrip Piercing Thoughts in Magic Penetration. This doesn't even include the ever-so-useful Armor Penetration that you get from Precision on top of the Magic Penetration. As with Piercing Thoughts, Battering Blows is a percent defense penetration, except that it is for Armor. Now, most carry champions start with around 20-25 Armor, which increases to 29-34 with flat Armor seals. With Battering Blows, which are 7% at max rank, this translates into 1.4-1.75 Armor Penetration for Armor within the 20-25 Armor range and 2.03 to 2.38 within the 29-34 Armor. Again, compare these numbers to the Cunning Mastery Precision, which have the same numbers for the Armor Penetration as they do for the Magic Penetration. Again, unless you are fighting a team of tanks and bruisers that build 50+ Armor per champion, Precision will always outstrip Battering Blows in Armor Penetration. Thus, for an Assassin, regardless of damage type, and especially for hybrid assassins, Precision is far and away a better mastery. Not only does Precision outclass the individual Ferocity counterparts in their respective defense penetration, it also is better than them combined. So, the next logical comparison after this is the Keystone abilities. Thunderlord's Decree deals (10*Champion Level)(+20% Bonus AD)(+10% AP) once every 30 seconds. Now compare this to Deathfire Touch, which deals 6(+50% Bonus AD)(+20% AP) over 3 seconds for single target spells, or 3(+25% Bonus AD)(+10% AP) over 1.5 seconds for AoE and DOT spells. The question you need to ask yourself as a player of an assassin is: do I want to deal large amounts of damage now, or over a period of time. Well, as an assassin, more damage now is the name of the game. An even better question, however, is when in the game do you want to deal the most damage? For mage champions like Morgana, or Brand, you are building for a strong mid to late game, but when you are Talon, Zed, or LeBlanc, you want to have your strongest moments early. This is where Thunderlord's Decree outstrips Deathfire Touch. Let's say you just hit level 6, got your ultimate, and haven't backed as LeBlanc. You probably have around 20-30 AP based on your runes. With Deathfire touch, you don't deal too much damage, as you haven't had the chance to really build AP yet, probably dealing around 6-10 damage over 3 seconds with your Q, 3-5 damage with your W. On the other hand, with your simple Q+W combo, Thunderlord's Decree deals a whopping 60-64 damage before you even back. In fact, if you can land three basics for poke over a max of 15 seconds, you can also proc it off of that alone (not as effective, but far safer). To deal this amount of damage with Deathfire Touch with the same stats, you would have to hit that enemy a minimum of 6 up to 10 times (based on AP from runes) times over a span over the next 30 seconds with a single target spell, or once every 5 to 3 seconds. Not only would that be far less effective as an assassin, it would require you to waste resources and place you in a position where you are constantly spamming spells at a regular interval, and landing said spells. Thus, in every way imaginable, Thunderlord's Decree is better than Deathfire Touch for Assassins. Maximizing your masteries is the difference between winning and losing a game. With optimized masteries that fit your champion and playstyle, you boost your ability to win situations, which further allows you to win games. By choosing a mastery tree of 12/18/0 as an assassin, you optimize your damage output and your ability to win fights over someone who chose 18/12/0. For champions who snowball, this is a make or break stat that changes the outcome of games.