By summoning forth a deluge, Amaterasu and Chibiterasu no longer need a water source for Waterspout. Thus, being a more versatile version of the base technique, Deluge can be used in situations when a body of water is not present, such as in battles, where its potential is best shown. In battle, Deluge can be used to constantly damage demons and halt them in their tracks. This technique is especially useful in battle against demons of the fire element, or when a Great Tengu is encountered. However, despite that Deluge has a longer duration than Icestorm, the latter has a more powerful and effective effect of nullifying the fire element of demons, as well as preventing the Great Tengu from entering Chaos Mode while also being its Floral Finisher, so constantly using Icestorm is more recommended than Deluge.
To use Deluge, Amaterasu and Chibiterasu has to draw the mark of Nuregami, || (two vertical lines). The longer the lines, the longer the duration of the rainstorm, but the more ink consumed.
"Use Waterspout to draw the shape of falling rain to bring on a Deluge sure to stop enemies in their tracks. Small drawings use 3 Ink Bottles and cause only a little rain. Medium drawings use 6 Ink Bottles and cause moderate rain. Large drawings use 9 Ink Bottles and cause a long shower. Coat evil in a nurturing and purifying rain!"
"Nice going, Chibi! You've learned a very useful skill! You can make it rain to slow down enemies with Splash! Draw two vertical lines like you were drawing rain to use it. The longer the lines, the longer it will rain for! But if you make it rain for a long time, you'll use up a lot of ink!"
After the defeat of Ninetails, Amaterasu can return to Sei'an City (Aristocratic Quarter). There, behind the entrance to Himiko's Palace is her handmaiden, tending the grave of the deceased queen. From the small pond near the handmaiden, use Waterspout to sprinkle its water onto the four gravestones in the distance, as a tribute to the deceased line of leaders. This will cause a rainstorm, and Nuregami will appear, granting Amaterasu Deluge.
Splash can be purchased for ¥50,000 from the shaman in Yakushi Village once nine migrants have moved there.
Spoilers end here.
Deluge being named as Splash in Ōkamiden may be linked to the game's theme relating children, for their tendencies to play in water bodies and splashing water.
When Deluge is used, the kanji 潤 (urumu, to moisten) appears.