Wolfbitten Captive is one that never gets ridiculous, but the ease in which it can double in size makes it very easy to use, regardless of the kind of deck you're using it in
Creatures who all they have is lifelink are not worth playing because you can get life from other sources that do much more
Obviously these sorts of effects are much less exciting when they cant target opponents directly, but some are worth a look for efficiency or synergy reasons Dire Flail and Hunters Talent come to mind
This will kill the land and allow blowfly infestation to put a counter on another land, which lets you put another counter on another land and so on
If your deck is full of expensive spells, try to play cheap card draw options to compensate for that
(Damage dealt by those creatures also causes you to gain that much life.) When this creature enters, create two 1/1 white Cat creature tokens with lifelink