Read the bat reps I don't have that much experience with either model yet, but they play on very different strengths, i'm more on the rippers tbh. If he's throwing chaff infront of you, you're at least getting rid of the chaff, and i am probably exaggerating the issue . Terradons offer little in the way of combat prowess, and their amount of shots are feeble to say the least. Drops rocks is there to clear one chaff unit and then you can start redirecting or locking down a warmachine with them. Rippers are the choice you want if you're killing stuff and want good support that'll last you for that one combat, more if you're lucky. Terradons are disrupters, since they can be faced right and still fly to where they wanna go without screaming banzaii. They can tie down a warmachine so it doesn't shoot your beasties, and they can provide a combat modifier via a rear or flank charge but probably won't wound stuff besides regular troops with stomp. They're cheaper, and hence is not too expensive to set in the way of something to redirect it, at the time rippers should be redirecting you want to have already killed them running into something dangerous (and likely smashing that too in a good combat). different roles... what do you need? The glass cannon combat monster, or the disruption minded more easily controllable Terradon? It should be said that both can kill a warmachine, a ripper is more easily distracted from doing so, but goes fast about it, a terradon holds it down so it can't shoot. Either way, you get results. Rippers can fight combat blocks as support. Terradons can support combat blocks that are fighting. I won't say more, since this is what i've read myself to understanding, my actual battle experience is still lacking and as such i can't tell you how to do well with those units, but i can tell you WHAT they do. http://www.ulthuan.net/forum/viewtopic.php?f=66&t=33028&sid=4fbbe90cc6402a6c86c43bf67536bcfa This latter is a ling to a great eagle tactica, you can almost use Terradons in the same way after you've used drop rocks / tied down a warmachine. And Skinks can defo be used much alike (though missing the fly special rule). It's a worthwhile read. Otherwise go through the Bat-reps on the forum! lots of tips to pick up from others Hope that helps!