Salve, Clarity, Tango: Starting Regen

INFO: A tango is an item that regens 115 health points over 16 seconds by 'eating' a tree. It costs 125 gold comes with four charges, and is pretty much your most basic form of regen.


USES: Other than the obvious HP restoration, tangos can also be used to destroy trees. An example would be if you are trying to pull neutral creeps through to a lane, and you need to get rid of that pesky tree blocking your way. Another example would be to escape Nature's Prophet's "Sprout" ability. It's fairly rare not to include this in starting items, unless you don't expect to be vulnerable to constant damage (while jungling, perhaps). Support heroes also find this useful due to the ability to cast a tango on another allied hero, giving them a single charge for their use.

INFO: A more potent health regen item, a salve heals 400 HP over 10 seconds. It costs 115 gold and it is a great item for early-game regen.

USES: The main difference between a salve and a tango is that the health regen of a salve is stopped when the hero it's healing takes damage. For this reason, it's not always the best decision for a role where you expect to trade a lot of hits. Salves are good for allowing you to stay in lane, and not have to return to the fountain. Of course, once the laning phase ends, heroes are better off relying on other items for health restoration.

INFO: A clarity restores 100 mana over 30 seconds. It costs 50 gold, and is another common starting item.

USES: Like the salve, a clarity's regen stops if the hero it's restoring takes damage. But as the only other forms of mana regen are percentage-based (heals less the less you have), or stat-based (only increases your base regen by a little, so not very good for quickly healing), the clarity remains the best early-game form of mana regen.
           
Not all heroes need grab this, though: as you will only have access to very few spells in the early levels, and those spells being relatively weak, only heroes with low-cooldown or utility (stun, slow, disable) abilities will get proper use out of this item. If your hero doesn't have at least one of those two types of abilities, it's often far better to wait until you can afford a better regen item.