Think of it like this.
To make Rylais, you need Blasting Wand, Amplifying Tome, Giant's Belt and 700g to form the Staff after you acquire all the item.
That 700g is what the recipe would cost in HoN/DotA. The reason for the existence of recipes is because of the courier unit, which allows you to shop remotely and have your items delivered to you. So say you have two components for an item, and you buy the recipe. You'd put it on the courier then run it over to you, and it'll form in your inventory.
Here is the full list of items:
http://www.heroesofnewerth.com/items.php
The items in Supplies, Accessories, Weapons, Relics, Outpost and Legendary shops have no recipe requirements. What you see is what you get. The Initiation, Support, Protective, Combative, and Morph Attack are all combination items. Some require recipes, others will form immediately after you have the necessary components in your inventory. (The support section on the site is actually broken)
A general description of what items in each Store does.
Supplies: Consumables, and starter items. This is where you buy most of your stuff right after the game starts.
Wards of Sight (orange): Gives vision. Max 4 wards in the inventory (shared by the entire team) at any given time. Replenishes at a rate of 3 minutes per ward.
Wards of Revelation (blue): Gives truesight. Unlimited. The detection range is as wide as the vision range on a Sight ward, but the vision radius is severely limited.
Dust of Revelation: Temporary truesight buff around yourself. You buy these two at a time.
Mana Potion, Health Potion and Runes of Blight: Restores mana, health and health respectively. The tradeoff between Health and Blight is one of speed over security. Health Potion restores 400 health over 10 seconds, but if you get hit, it cancels. Usually you sit back a safe distance while it works. Runes of Blight comes in 3 charges, each of which heals 115 health over 16 seconds. But it doesn't matter if you get damaged or not. Also they can be used to cut through trees in a pinch. Mana pots restore 100 mana over 30 seconds. It will also cancel if you get damaged.
Homecoming Stone: Also referred to as TP. Using a homecoming stone lets you warp to any friendly non-player built structure, usually used to defend but also to travel somewhere while a teamfight is building. It will choose the building closest to where you click, so be careful to click the right location on the minimap. (You can also find the tower manually and click it but that is time consuming) You can buy as many as you can afford but you can only use them once every 60 seconds.
Monkey and Winged Courier: Starts out as an item in your inventory. needs to be "used" to spawn the monkey. It can be used to ferry items from the fountain to you while you're in the field. It's very weak however, and any items on it when it dies are dropped. This doesn't happen often but when it does, people rage so hard. Flying courier is an upgrade you buy. You place the recipe on the monkey then click "Upgrade Courier" or use the "Q" hotkey when the monkey is your active unit, and it turns into a Winged Courier. The winged courier has a speed buff, and an invulnerability shield.
Mana Battery and Bottle of Tears: Your two main options for non-consumable regeneration. Mana Battery gains charges every time an opponent near you casts a spell. You can expend the charges (max 10) to restore 10 health and 15 mana per charge to yourself. Do not underestimate the strength of a mana battery, it can turn around a fight when you need that nuke to win a fight but don't have the mana to cast it.
Bottle has 3 charges, which are filled anytime you're in range of the fountain. Each charge restores 135 Health and 70 mana over 3 seconds (damage interrupts). It can be also used to hold a rune for up to 2 minutes, at which point it will be used and the bottle will be refilled.
Accessories: Hybrid Stat items, which grants Agi, Int or Str. There are generally 3 types of Hybrid Stat items.
150g: Buys you +3 Agi or Int or Str.
450g: Buys you +6 Agi or Int or Str.
1000g: Buys you +10 Agi or Int or Str.
There are also items that give bonuses to all 3 stats simultaneously. They go:
53g: +1
185g: +2
540g: +4
2100g: +10
Weapons: Damage or armor items, sometimes with an additional effect. The exceptions to this are the Hatchet and Stout shield, neither of which gives you stats but their passives do improve your laning abilities by preventing damage or making farming easier, respectively.
Relics: Everything else. Boots, base regen items and miscellaneous other items that don't really fit anywhere else.
Outpost: A collection of items from the aforementioned shops. They can be found bot lane on Legion side, and top lane for Hellborne.
Legendary:Very expensive items, usually used for recipes for mid/lategane. There are the boosters (as they are known in DOTA). They give, +250 mana, +250 health, and +200 health/+150 mana and cost 900g, 1100g and 1200g respectively. The +25 items, which cost 2700g for Int, 3000g for Agi and 3200g for Str. The +46 and +60 damage items, which cost 2200g and 3800g respectively. Warpcleft, which costs 2100g for +55 attack speed. And the two components of sustainer, Manatube and Healthtube, which cost 875g and grant +5 Health Regen and +100% Mana Regen respectively. Note on mana regen. There are two kinds, flat and percentage. Percentage boosts are additive. So getting two mana tubes will give you +200% mana regen. Flat regen, like the aura from Ring of the teacher, gives you mana per second.
Initiation: Early game combination items.
Fortified Bracer, Soulscream Ring and Amulet of Exile: These are the +3/+3/+6 items, which are basically some mixture of Int and Agi and Str. They are built off of any of the 150g +3 items and the 185g +2/+2/+2 item and the corresponding recipe. Bracer costs the most, Ring costs the least.
Power Supply: A better mana battery that gives +3/+3/+3.
Blood Chalice: Solves most heroes' mana problems by sacrificing health for mana. Also gives +3 Str and +3 Int.
Sustainer: Philosopher's stone but way more expensive.
Firebrand and Arcana are really only there to be built into better items.
Alchemist Bones: Lets you instantly kill a creep for bonus gold. Think Gangplank's Parrley. The bonus gold depends on how much the creep is worth, so go for the big ones. Stores up to 2 charges. Generally too expensive except for junglers since they're hanging around big creeps all the time.
Striders: Boots of Mobility but way faster. Primary means of roaming for heroes that don't need/get much farm. Your best friend as a support player
Steamboots: Gives +10 to a single stat, movespeed and attack speed. Can be toggled to switch between stats. Some people like to show off and switch to Str stat while dying to gain extra health and troll his gankers.
Ghost Marchers: Gives movespeed and damage. Can be activated to grant unit walking and a speed buff (like Ghost on boots)
Plated Greaves: Boots that can be activated to give a temporary damage and damage deflection buff. Generally useless except in highly organized play and certain push strats.
Post Haste: Can be activated to teleport to any friendly non-hero/non-ward unit. 60 second cooldown, shared with TP/Homecoming Stone. Generally too expensive to get in a normal game but if you're uber pro you get one just to troll people.
Support: These items usually confer some sort of ability that lets you disable. Some of them can be used for other things, like summoning minions that give truesight or pushing someone forward or a group heal. Most of the items are Int, but not all. Notable items are Tablet of Command (pushes an allied or enemy hero forward by 500 units, interrupts channeling, can be used to cross obstacles), Storm Spirit (disables an allied or enemy hero for 2.5 seconds, preventing them from being targeted), Ring of Sorcery (activate to restore mana to you and all your friends), Puzzle Box (can summon two helpers, repeatedly purchasing this recipe after the item is made will upgrade it up to level 3, one of the minions at level 3 grants truesight), Refresher Orb (refreshes all non-item cooldowns), Barrier Idol (grants all nearby allied units a shield that absorbs 400 spell damage) and Totem of Kuldra (turns enemy target into a sheep for 3.5 seconds).
Protective: These items are defensive/tank items. The notable items are Helm of the Black Legion (hands down the best tanking item in the game), Assassin's Shroud (activate to give invisibility and movement speed), Nullstone (Banshee's Veil with a shorter cooldown) and Shrunken Head (also known as BKB, gives magic immunity).
Combative: These items help you to do lots of damage. However, most of them also have secondary effects/activated abilities that work better for this hero or that. There's nothing like Infnity Edge and Phantom Dancer here, you pick the item that best suits your needs. Notable items are Spellshards (upgradable, gives your spells MRpen), Hellflower (which silences skills AND items), Geometer's Bane (which grants you two illusions), and Codex (upgradable, gives you a progressively stronger nuke).
Morph Attack: These items change the way your attacks behave. Think of items like Wit's End (old one and new one), Frozen Mallet, and pretty much any lifesteal item. Unlike in LoL, HoN attack modifiers do not all stack. They are split into 3 types. Attack Modifier (lifesteal, slow, armor degradation), Mana-Depletion (like old Wit's End, but actually viable) and Bashing (which gives a chance to stun). Oddly enough, the item that grants Bashing, Brutalizer, is in the Combative Shop.
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