League-of-legends – a good item build for support with Blitzcrank

So your basic question seems to be: Surge or Promote? This is a rather strange question as those two summoner spells fit very differently into the current Meta-game. In fact, I don't believe there is ever a hero I could imagine having to choose between those particular spells as they serve very different roles. So instead, let's assume that you want to know when these two spells are appropriate (and not make a choice between them).

Surge

Surge is a rather recent introduction into LoL and is still having its place in the meta-game examined. While it does act as a much needed steroid for a number of champions missing one (eg. Twisted Fate or Teemo), it suffers on champions who require a lot of farm (i.e. most carries). In comparison to spells like Ignite and Exhaust, Surge (while scaling better) just doesn't guarantee kills the same way through early/mid-game. Now, it's true that Dominion has a shortened early/mid-game, but it's just as true that it has a shortened late game (where this spell really shines). As a result Surge is frequently not the best choice for champions (even carries).

• When to get it? When you're the main DPS and you don't have a built-in steroid

• When to avoid? When you're a carry who needs kills to make it to late game

Promote

Promote is another spell which hasn't yet found a good place in the overall meta. However, having been around longer, there are more obvious cases where people use it (i.e. in Dominion going bottom against a Champ who has trouble clearing lanes early on, like Tryndamere or Yorick). Given Promote's role in taking down towers, it's no real surprise you see it more often in Dominion than Summoner's Rift. Usually, you want Promote to push your creep wave into a tower allowing for a better engagement at a node. This frequently means you find Promote on Champions who have trouble clearing lanes or who are good initiators. A Champion that requires more farm or is main DPS (i.e. a carry) is a less likely place to find promote as it doesn't fit their role well.

• When to get it? When your team lacks a lot of lane clearing ability (or against a team which lacks it)

• When to avoid? When you're filling a more important role (i.e. Carry)

Garrison

I'm surprised you're reading a lot of information that Garrison is a poor choice; it is quite a good spell. The problem with Garrison is that it really only shines is defending nodes in Dominion. Very frequently people don't do this (usually because it's less exciting). However, there are a large number of places where your team can really benefit from Garrison (solo bot, or even defending top). Garrison can break a channel (from further range), stop a wave push, or even heal a node, all very useful things in Dominion. Even if it only forces the other team to break off an engagement then it is directly translating into victory points (something few other spells do).

• When to get it? When you're running a 3 Node defensive strategy or against a team with a lot of floaters (e.g. Rammus)

• When to avoid? When you're filling a more important role (i.e. Carry) or you're going for a more aggressive strategy (i.e. running floaters)

Flash vs Ghost

Both of these are excellent spells (and there are even times when you might get both), but in Summoner's Rift, at least, the current meta-game has stabilized on Flash being invaluable. This is largely due to two factors:

1. Flash lets you get out of (or into) range of abilities and champions
2. Flash lets you "jump" over the twisting terrain in SR

However, in Dominion both of these reasons are less effective. The terrain in the Crystal Scar has fewer features you can "jump" with Flash, the faster game play means champion deaths are less impactful (thus saving, less important). While still a great spell, Flash is nowhere as dominant in the Crystal Scar as it is in Summoner's Rift. Instead, two other features dominate The Crystal Scar which make Ghost a frequently more picked spell:

1. Non-linear attack routes
2. Contested towers

Having multiple paths to engage (and less vision) often means you are forced to move to positions very quickly. This is the reason champions like Rammus are so frequently banned. What's more, it's frequently a strategy to rush to the top tower at the opening of the game to assert the defender's advantage. In a rush strategy (fairly common) it is necessary that most of the top defenders have Ghost to out pace the other team. As a result Ghost may not enjoy the same dominance that Flash has in SR, but is still a powerful spell (and a frequent choice).

• When to get it? Both Flash and Ghost can be great spells on any Champion

• When to avoid? Only when you have something which is much higher priority or more synergistic with your strategy (like Zombie Karthas was).

The point of gold per 10 items is to increase that gold generation early since you will not be getting creep score. You get a philosopher for mana regeneration and heart of gold for health bonus for your survivability. Generally you want to build a gold per ten on a character if it is beneficial for you in what it builds into generally. Stone builds into Shurelya's Reverie, heart finally into something useful, Locket of the Iron Solari. These are both useful to a team as a support. Kage's pick only builds into deathfire, not as benificial to team, and Avarice Blade also gives gold per ten but builds into ghostblade which only gives benifits to holder again. You would want to sell pick and avarice blade later on for other items due to this fact which is not very viable. From the league wikia, the items pay for themselves after roughly 12 minutes. The gold you have to put in is locked up for 12 minutes each so there are more viable options to buy.