Unfortunately, Infect has fallen somewhat to the wayside in Modern lately, but it remains a competitive strategy for players who aren't concerned with running the best deck out there
As a result, Aerodactyl EX is our go-to for a Lucario deck
And just look at all the Knights in the format: Benalish Knight, Burning Shield Askari, Cadaverous Knight, Fallen Askari, Femeref Knight, Knight of Valor, Searing Spear Askari, Shadow Rider, Southern Paladin, Suq'Ata Lancer, Zhalfirin Commander, Zhalfirin Crusader, and Zhalfirin Knight
The tricky thing about this card is timing: having to pay two mana before casting an impactful spell could throw off your mana curve if you're not careful, making this one you'd be better off holding until the late game than casting as soon as you have enough to warp
Aitsu is particularly notable, not just because of its horrible stats for a Normal Monster that you need a tribute for, but also the way that they encourage you to play it and also their appearances in other places in the card game