Guide to optimising stats, heals and regeneration

This guide is about changing your hero's stats to make better use of heals, consumables and regen, and also to make the best use of your available mana and hp. While that may sound very difficult and complex, it's pretty simple, and most easily explained with an example:

Let's say you're a 800 hp hero with a Point Booster and a Healing Salve. After escaping a gank, you're down to 200/800 hp. Now if you use your Salve, you're only going to regen back to 600/800 hp. However, if you drop your Point Booster, your hp will become 150/600. Now if you use the Salve, you heal 400 hp, and go back to 550/600. Pick up your Point Booster and you have 733.333/800 hp. Simply by lowering your stats for the duration of the heal, you have effectively increased your healing Salve's potency from 400 hp to 533.3333hp!

That's basically what this guide is about: using your stats to decrease hp/mana loss and to increase hp and mana gain. In DotA, nearly all stat-changes result in a relative shift in current hp and mana. What this means is that how much actual hp or mana you gain from a change in base hp/mana depends on the percentage of hp/mana you have. If you're at 50% hp and you pick up a point Booster, you'll still be at 50% hp, but the amount of actual hit points will be higher.

The guide is divided into two parts: The first part explains how stat manipulation works, the second part discusses specific items and skills that lend themselves to this type of manipulation.

HP-management

1. Before taking Damage, make sure your hp is at it's highest. This very obvious point is required for abuse further down the line, so before you enter battle, make sure you are carrying all your HP gear, set your Treads to STR and activate any shape-shifting skills which give more hp.
Besides the obvious fact that more hp equals a bigger chance to survive, by increasing your hp you're decreasing the amount of damage you receive relative to your total hp.
2. After taking damage, lower your hp before applying heals/regen.
Just as you can decrease the potency of damage by increasing your hp, you can increase the potency of fixed heals by decreasing your hp. The starting example clearly illustrates how you can exploit healing items to give you more hp. The same also counts for "regular" regen: Tangoes, Ring of regen, Helm of Iron Will, etc. all give fixed hp, so lowering your hp will increase their efficiency. An example:

I'm a level 6 Antimage with Treads and a packet of Tangoes. My hp is 834 with PT set to STR and 644 with PT set to something else. I get nuked for 400 damage, but luckily I had PT set to STR(434/834). I eat a Tango. Now let's compare what happens if I switch my treads and what happens if I keep STR: STR: Starts with 434/834 hp. 36 STR. HP regen: 0.25 + (36 * 0.03) + 7 = 8.33 hp/sec 8.33 * 16 = 133.28 hp. HP after 16 seconds: 567/834 Relative HP after 16 seconds: 68% INT: Starts with (52% * 644) = 335/644 hp. 26 STR. HP regen: 0.25 + (26 * 0.03) + 7 = 8.03 hp/sec 8.03 * 16 = 128.48 hp. HP after 16 seconds: 463/644 Relative HP after 16 seconds: 72% Hp after switching to STR: 600/834 (33 hp extra gained!)

Lowering your hp can be done by dropping anything that gives STR or HP, switching your Treads away from STR and even by waiting for certain shapeshifting skills to end.

Mana-management

1. Before using mana, increase your maximum manapool. For all spells except Ball Lightning, this will decrease the relative manacost of your spell. The only feasible way to increase your manapool (besides obviously carrying all your INT items) is to switch Power Treads to INT, so I'll mostly be referring to INT Treads here.
2. Before using fixed mana regen/heals, lower your manapool. Drop any INT and mana items on the ground and switch PT away from INT. While this works best for fast mana heals like Chakra, Bottle and Arcane, it also works for slower stuff like Brilliance Aura and Clarity Potion.
3. If you have percentage-based mana regen, keep your INT gear, but drop fixed-mana increasers on the ground (basically boosters). Dropping INT doesn't help because %-based regen works with your INT.

Lvl 6 SK Treads Wand: 24 + 10 INT = 442 mana Hellfire Blast: 302/442 = 68.3% 0.0.4 * 34 + 0.01 = 1.37 mana per sec. 302 + (1.37*10) = 315.7/442 315.7/442 = 71.4% 213/312 = 68.3% 0.04 * 24 + 0.01 = 0.97 mana per sec. 213 + (0.97*10) = 223/312 223/312 = 71.4% As you can see, without %-mana regen, more INT doesn't matter for the relative amount of mana gained.

In Practice

How does all this apply to actual DotA? In this part I'll point out some uses of the theories explained above for specific items. Of course, dropping all your items is not always possible, in fact, it's not even always desirable. Each of these tricks takes a bit of time, time which can often better be spent farming, moving about, ganking, whatever. Before tossing out your Branches to get a couple of extra points of heal from your bottle, you should ask yourself if the extra hp/mana is worth the time lost. Time is money after all.

Urn of Shadows, Healing Salve, Bottle Drop all your hp items, Switch your Treads to AGI, then use the heal. Since these heals get disabled by damage, you need to stay out of combat while using them, so it should be safe to drop some gear. Luckily all of these heal pretty fast.

Magic Stick/Magic Wand Since this heals both hp and mana, you should always lower your hp and mana as much as possible, whenever possible. If you use a charged up stick to heal up pre-combat, you can usually afford the couple of seconds it takes to drop and pick up your stuff. Obviously, this cannot be done in a battle, but one trick you can pull off in combat is switching your treads to AGI while you use Stick/Wand. This will earn you a couple of hp and mana points when you switch back to STR/INT.

Power Treads Switch it to AGI when using Bottle or Stick(or any other hp/mana heal). With most heroes, I find it best to keep it on INT at the start of battles. After the first spell/spell combo, switch it to STR or AGI, depending on the situation. If a chase develops, you can keep switching to INT before casting your spell(s) and then switch back for hp. Outside of battles, I usually keep Treads on INT if I have percentage-based manaregen, unless the regen is wasted (Mortred/Huskar for example).

Soul Ring Very abuse-able, especially with Power Treads. Before activating Soul Ring, increase your hp by switching to PT STR. This automatically lowers your manapool if you had your PT on INT, which is good since a low manapool means a relatively large "heal" from the ring. As soon as the ring is activated, switch to PT INT before you use your newly gained mana. Even if you don't use the mana, Soul Ring will only reduce 150 mana, so you'll make a small profit.

Armlet of Mordiggian Armlet works differently from most items, since it always gives 25 STR worth of hp when activated. This means that activating it, even at 0 health, will give you 475 hp. Unless you're Huskar, turn Armlet on at the start of battle. If you're Huskar, turn this on after using Life Break, since Life Break is percentage-based. Doing so will save you 190/157/119 hp. Once your hp drops below 475, you can deactivate-reactivate Armlet to heal you for 475 hp.

You'll find that as the game progresses, these tricks become less and less effective because the importance of small heals diminishes and because the amount of manipulable stats relative to your total hp/mana diminishes. Nevertheless, especially during the earlier stages of the game, knowing these tricks (and remembering to use them) can help you land that extra shot, toss that extra stun, and tank that tower just a bit longer. Every point of hp and mana that you can squeeze out of your items gives you an edge over your opponents.

In closing, I hope everyone can in some way benefit from this guide. If you were already aware of stat-manipulation, I hope this guide still contained a trick you didn't know about. If this was all new to you, don't waste your heals any more!
If you have anything to add, feel free to post your additions.