While there are some Commander applications with the Avatar Horror, the card is seeing the most play in Standard within Four-Color Zur and Domain Ramp, which uses Zur, Eternal Schemer to give your Overlord cards deathouch, lifelink, and hexproof
The price returned corresponds to the cheapest available regular printing of that card not a specific set or edition
Flanking is a mechanic introduced in Mirage that has a very similar flavor to horsemanship since it most frequently appears on cards featuring warriors on horseback, but the two mechanics are very mechanically distinct
In total, over the past month, over 728 near-mint copies of Champions from Beyond have been sold
A two mana 2/1 with Flash and Flying is a playable card, and this can often generate a 2-for-1 by blanking a removal spell
This concept was shorthanded to the daybound and nightbound mechanic for Innistrad: Midnight Hunt and Innistrad: Crimson Vow