User blog comment:Zilla4444/The Sheen/Trinty Force Dilemma/@comment-1120494-20120626235124

AD means Attack Damage.

No idea whats so "Attack Damage" about Armor & Magic Resistance.

Also Armor & Mres is nice on every champ in the whole league.

Also you dont need always both of them.

Also there are already items which gives you both for the few cases you need, like Aegis & Guardian Angel.

I dont like the idea about Trinity with HP, Armor AND magic resistance. This would probably the cheapiest and best tank item in the game, which never was the intention and never will be.