TigerDude
Explorer
I think everyone has covered it, but in summary it's neither inefficient nor useless. Yes, a rat or spider is a great scout. And yes, scouting means splitting the party. Sorry cleric, keep your heavy plate mail where you are, I'll go see what the enemy camp is like. Note that your spider or rat now has your hitpoints, plus temp hp, so you might be a rat, but you're a very hard-to-kill rat. Other than this, throwing a concentration spell and then turning into something that can easily hide or otherwise not be targeted is a great option. Dont forget burrowing beasts.