We're living in a world where [url=https://m.youtube.com/watch?v=VCYL-HGmGck]B.E.S[/url] have a field spell that makes all their monsters untargetable by anything for literally no cost, so it's not too unreasonable for it. And if it did have that effect you'd have to specify that it's a quick effect so it can chain onto things like twin twister and mst, which are instant spells and therefore spell speed 2, unlike field spells that are spell speed 1. Minor quirk of the rules, there.