­Armor of Thorns + Blade of the Bloodbraided

Well, two things that sound like equipment; we're clearly making some kind of knightly raiment here.

The first is... a Giant Growth variant; can be permanently +2/+2, or you can use it at instant speed for a really horribly worded temporary boost.

The second is... double strike and trample - and needs a sacrifice to equip. Ouchie.

So I'm thinking an enchanted suit of armour that eats its wearer.

Bleh; I can only get about half the words on that I'd need for this. It needs a second way to get it on. ... Can I put 'or' in a cost? Let's try that.

It's still not quite there; I really do want a way to get it into play the first time, more quickly. Oh well.

Hey, that was quick! :)

So the activated ability is supposed to be instant speed?

I don't get how the two abilities are supposed to interact. The ability to move the Equipment around by sacrificing the equpped creature is far less interesting since you sacrifice the equipped creature anyway at end of turn (and the same for whaterever you attach this to by activating the ability).

Maybe something like 'kicker for equip costs': > When ~ becomes attached to a creature, you may sacrifice a creature. If you do, it also gains double strike and trample for as long as ~ remains attached to it.

? That way the initial equip cost can be lower as well.

Also, "or" in a cost works: Heartwood Shard