Razor, lupical, raised by wolves, is a physical dps. There are a number of other 4 star dps units, including Heizou, Ningguang, Kaveh, etc.
Some of these 4 stars need to think hard about the crimes they committed and why they were relegated to 4 star status.
Shares some similarities with Cyno (NA+E gameplay) and Eula (E stacks).
NA is called Steel Fang. Q is called Lightning Fang. These would have been better names for Baizhu's kit skills. Razor's birthday is 9/9. Perhaps this would suit Xingqiu or Baizhu more? Actually, if Razor is a 4 star, then Baizhu should have been a 3 star, since Baizhu's crimes outweigh those of Razor.
His tap E gives him a sigil. Each sigil gives him 20% more ER, up to 3 sigils. His hold E consumes all his sigils and generates an additional 5 energy per sigil consumed. His tap E has a 6s cd, while his hold E has a 10s cd. One passive will decrease E cd by 18% and makes using Q reset E cd. Another passive will increase his ER by 30% when his hp is below 50%.
His Q has 80 energy cost and summons a wolf spirit that does coordinated electro damage alongside Razor's NA. The Q also gives him ATK speed bonus and electro RES bonus. It lasts 15s, same as Noelle and Xiao's bursts.
In retrospect, given the scaling on the wolf electro damage is quite low (scales as portion of NA damage, 50% NA damage at lv13), Razor's Q does not really do much for him besides the ATK SPD bonus (which is somewhat important as Razor's NA are quite slow).
But Razor does not really need his Q to function as a unit. His Q will not buff his damage by much, but rather just make him attack somewhat faster.
C1: gaining particle/orb increases NA dmg. C2: increase CR by 10% against opponents with less than 30% hp. C4: using E will shred DEF by 15%. C6: every 10s, sword will charge up and make NA deal 100% atk as electro dmg; outside of Q, it will also grant Razor a sigil.
Same build as Eula. Because Q resets his E cd, he can take advantage of 4p Pale Flame effect. Alternative is 2p Pale, 2p Bloodstain.
Examples: Raiden-Nahida-Diona-Razor, Raiden-Mika-Rosaria-Razor. Common supports include Mika, Rosaria, Diona, Qiqi, Raiden, Kuki, Layla, etc.
Can function in similar teams as Eula, with some key differences: Eula is cryo and needs an electro applicator for superconduct, whereas Razor is electro and needs a cryo applicator.
As of 3.5, the game has many consistent electro appliers (via E) such as Raiden, Yae, Kuki. However, there are not as many (if any) consistent cryo appliers via E. Qiqi and Layla are as close as one gets, but still. See subdps for details.