Tartaglia (alias Childe, original name Ajax) is the game's premier enabler, who can function both as a DPS and as a support. The duality extends to his own kit, where he can switch between ranged and melee stance with his skill. This duality makes him one of the more versatile units in the game.
Being the first character with a 2nd rerun and appearing in Mondstadt, Liyue, and Inazuma, Tartaglia embodies a different kind of universality, an element that exists across the world. In the game's own words, he represents a force with the ambition to 'conquer the world'.
What does Tartaglia have to do with Liyue? Who are the Tatars in Chinese history? They refer to the various northern groups such as the Mongol and Man people who have ruled over China during the Yuan and Qing dynasties, establishing two of the largest empires in Chinese history. During the Yuan, of course, the Tatars did much more, conquering as far as the west as well.
Genshin developers have said that Childe's sword fighting design during his skill stance change has been inspired by Cossack shashka techniques.
Usually one wants to stay in this stance for at most 15 seconds before swapping off, to avoid the cooldown from becoming a year.
The skill is unique in that it turns Tartaglia from a ranged to a melee character. With his ascension passive he applies Riptide on CRIT hits, so it is beneficial to invest some CRIT Rate into Tartaglia.
C1 reduces the CD of his skill, which allows for more comfortable gameplay, but still one does not want to stay in this stance for more than 15 seconds.
C6 enables a DPS Childe by resetting the CD of his skill. However, for a more support/enabler Childe, it is not necessary. Childe will do his job effectively even at C0.
Note Tartaglia will not be able to plunge attack while in this stance. (This may be due to the ambiguity in Childe's exact weapon type during this stance. Genshin has said before that Childe's hydro weapons are partly inspired by shashka swords.)
The burst has higher scaling than Hu Tao's burst and has greater flexibility. One can use it in ranged stance to apply riptide, do a 6m AoE blast, and refund 20 energy. One can also use it in melee stance for greater damage, greater AoE (8m radius), and to clear the Riptide status from opponents and even trigger extra Riptide damage.
So one can use Childe's burst any time with benefits in either case. By contrast, for Hu Tao, you almost never want to use her burst outside her skill buff (as you lose out on the ATK buff; you usually want to use it near the end of Hu Tao's skill).
Master of Weaponry is unique in that it increases the level of your own party members' normal attacks by +1. Note it does not work in co-op mode for other players (and thus does not stack).
Still the skill can be very useful for supports such as Kazuha who rely on normal attacks (plunging) and even DPS units like Xiao who benefit from the extra level.
The 4-piece Heart of Depth is Childe's BiS for E dps (which is the core of Childe's uniqueness). The Nymph's Dream is also good for balancing between E and Q, and the effect is reminiscent of Childe's Polar Star. Nymph gives atk (but Childe is usually ran with Bennett), but less dmg bonus than HoD. Nymph's stacks last 8s (fine for Ayato's short 6s window), but HoD's 4p effect lasts 15s. It is possible Nymph will be good for future hydro units too (maybe from Fontaine, but judgment is reserved). What Nymph brings is the possibility of 2p HoD/2p Nymph for 30% hydro dmg bonus.
That said, a 2-piece HoD / 2-piece Noblesse is viable for a burst support Childe. A 4-piece Shimenawa is somewhat viable for Childe, but usually not optimal since Childe's burst does a lot of damage.
Look for ATK% on the sands, Hydro DMG Bonus on the goblet, and CRIT on the circlet. The best substats are CRIT > ATK > EM. Childe does not need too much ER since his burst can refund 20 energy already.
Unless the Nymph set is for future hydro character as well, its release in 3.6 can be seen as a desperate attempt to split people politically, to divide and conquer, to force people to be closer to one group of people and not another. But the Nymph set does not change the fact his name is Childe. It will not change who Tartaglia is.
For a master of weaponry, there is much to say about Childe's weapons.
Tartaglia has 3 top-tier 5 star bows:
Other 5 star bows are viable options but pale in comparison to these big three.
Tartaglia's best 4 star option is:
Other 4 star options are:
Note one can use Venti in lieu of Kazuha or Sucrose, but usually the CC Venti provides is overkill, and Childe may sometimes not be able to hit enemies trapped in Venti's burst while in melee stance. For this reason, Kazuha and Sucrose are usually preferred, while Venti can be used in the other Abyss team.
Yun Jin can also be used to buff Childe's NA.
Since 3.0 with the introduction of dendro, Childe's legacy fireworks and EC teams can be transitioned to burgeon and hyperbloom variants. Childe, being hydro, is a unit that has benefited a lot from dendro, specifically in hyperbloom teams where he acts as a driver for creating hydro cores. Childe still has the strengths of quadratic scaling on E, his classic international vape team, but with Sumeru and dendro he now has more options in teams.
Although Childe does not need a hydro battery (can apply hydro on E), he does not benefit from hydro resonance (hp buff), and one still has to be careful of the E cd.
These other teams are more for fun or exploration, but are also viable in Abyss:
We assume level 10 E and level 90 Childe with 4 piece HoD and a Hydro DMG goblet (for a total DMG Bonus of \(28.8+61.6+30=120.4%\) for normal/charged attacks during melee stance).
For now, we ignore other buffs such as VV or Bennett, and we assume no burst for Childe and ignore Riptide (though with these factors, the team will do more damage). Because Childe applies hydro too fast, most of the time he will not be vaporizing his normal attacks.
We assume he does a 6 hit combo (N6) with no charged attack (note that depending on the weapon, other combos involving mixing in a charged attack can be more optimal, but will not differ too drastically in application). The total scaling for the 6 hit combo is 642.77 at level 10. The damage scaling for this combo is then $$z_C = (1+1.204)*642.77 = 1416.66508$$ We assume he can do this around 4 times within 15 seconds. The cooldown and downtime will be \(15+6=21\) seconds (this timer starts after Childe leaves melee stance, and this is the key point). The length of the rotation is \(15+21 = 36\) seconds. The DPS is $$x_s = 4z_C/36 \approx 157.4$$ Childe's main role is as an enabler.
If he spams his CA, he can do around 10 N1C1 (1 normal followed by a ca which consists of 2 hits) combos with a cd of around 21s or before stamina runs out. The dps is $$x_s = 10*(1+1.204)*(76.8+119+142.3)/36 \approx 207$$ So spamming gigachad ca is more optimal than just splish splashing na. This is also why the rust is not necessarily that good for Childe, since he relies on CA as well. Rust is more suited for Yoimiya.
Childe will also do some damage when switching stance. This is ignored in the above calculation.
The riptide from the E (riptide slash) procs once per Hydro hit (whereas the riptide from his ranged ca, riptide flash, procs 3 times). Riptide slash is considered E damage. It procs once every 1.5s. At level 10 it adds an extra scaling of 119%. Note it is not NA/CA damage so the damage bonus for it is \(28.8+61.6=90.4\%.\) Suppose when spamming 10 CA the riptide slash also procs 10 times total. The recomputed dps is then $$x_s = 10*(2.204*(76.8+119+142.3)+1.904*119)/36 \approx 269.9$$
Since Childe's riptide has quadratic scaling, it will actually do more damage the more enemies there are. The above dps computations are considering single-target damage. It would also be the dps for linear scaling (damage per enemy). If we factor in his aoe damage (when he hits multiple enemies at the same time), if there are n enemies the dps is $$x_s = 10*(2.204*(76.8+119+142.3)+1.904*119n)/36 \approx 207 + 62.9n$$ So his na/ca have linear scaling, but the riptide component has quadratic scaling, resulting in the factor of n above. Quadratic scaling has total damage \(An^2\) so the damage per enemy is \(An\). The riptide slash aoe is 3m in radius, so the enemies will have to be pretty close together for this quadratic scaling to kick in. This becomes more possible with the help of anemo cc units like Kazuha or Sucrose. Riptide is the key reason why Childe is better than Xingqiu (at c0 or any constellation for that matter).
But this is the way the game balances scaling: you can have quadratic aoe scaling, but the aoe is going to be smaller than other aoe abilities that have linear scaling. Many aoe abilities such as Xiangling's burst or other bursts in the game have linear scaling but have larger aoe (>3m radius). As is often said, Genshin also balances Childe's dps by making his cd and downtime quite long for a rotation. This is why Childe's C6 is not bad, by essentially reducing the downtime to 0.
Some other notes on riptide: the riptide status can be applied by Childe's ranged ca, crits on Childe's E (from his passive), and his ranged q. Riptide burst spreads riptide when an enemy with riptide is defeated. It is considered part NA damage. It is ignored in these calculations. Of all his riptide abilities, riptide slash (E riptide) arguably contributes the most to Childe's overall dps.
When there are n=4 or 5 enemies close together (within 3m of each other), Childe will start to out-dps Ganyu, Hu Tao, and C6 Xingqiu. If there are n=6, Childe becomes one of the top C0 dps units in the game. How often is it that 6 or more enemies are close together in the current game? Regardless, this is theoretically speaking, a thought experiment. Childe really does not need C6. The most op thing in his kit is with him at C0: the riptide.
We assume Level 10 Q and that it vapes (e.g. usually in a Xiangling team, Childe will start a rotation by vaporizing a ranged q). It costs 60 energy and has a 15s cd. If it is ranged, it refunds 20 energy and applies the riptide status. The advantage is that ranged bursts are easier to spam on cd. The dps is $$x_b = 2*681*(1+.288+.616)/15 = 172.8832$$ which is a substantial portion of Childe's overall damage. This is ignoring EM boosts. His burst may not always vape (e.g. in a Beidou fireworks team).
If it is a melee burst, the scaling is higher but there is no energy refund. The dps is $$x_b = 2*835*(1+.288+.616)/15 = 211.9786666667$$ This ignores riptide blast damage (if opponent has riptide, the melee q does extra damage). But factoring that in gives $$x_b = (2*835 + 216)*(1+.288+.616)/15 = 239.3962666667$$ Childe's q applies strong (2B) hydro, so it will most likely clear any pyro status on the enemy, so we assume the ensuing riptide blast will not vape.
Factoring all his damage in (skill + riptide slash + burst), his total dps becomes $$x_s + x_b = 207 + 62.9n + 172.8832 = 379.8832 + 62.9n$$ As \(n\ge 1 \) the total dps is at least \( x_s \ge 442.7832 \) so Childe is a better dps than Ganyu and Hu Tao.