I love how everyone's thought process is fixated on one map alone. On cat... this is an awful idea for the reasons mentioned above.... But consider a map like leviathan, where there are 2 portals per team, and 2 portals at the mid point of either side. Those portals are also in areas that are not being contested, as in battles take place near the damage flag and shop flag. So in this scenario, yes heavens wrath or ice is great because you can farm a lane that no one is sitting in anyway unless they are actively going to lock down that flag, in which case there will be no more creeps coming from it anyway.
But in general, or should I say, on cat. This is a terrible idea. The less xp / money your allies have, the less chance you have of holding down a side and the sooner you need to go shopping / heal to compete. Once you leave that lane..... goodbye tower, goodbye flag, and if on the proper side, goodbye gold mine. Leading to more crap down the road - while your farming ally continues to syphon money from the team as a whole by continuing to use those spells / favors.
Plus, for reg / tb there's a bunch of other favor item's I'd rather be using that don't hurt my team, make my character stronger, and are applicable late game. 250 dmg late game = ehhhhhh when your opponent's have 5k+ health and sigils etc. I could use mard's hammer if I wanna go right click - lazy auto attack reg for dps early, staff of renewal on leviathan if I want more mana / health and lower cooldown for more snipes, snipe as enemy runs in, snipe while ally battles, snipe when he tries to run away - all from the opposite side of the stage. Or, I'd go poison dagger to slow people down so my teammates get more hits / if they have lots of interrupt / stop spells such as grasp / charm and I didn't plan on points into maim anyway as slow does not stack but speed does.
Wrath makes no sense on TB as you can kill a creep wave with a level 2 ice storm. Why get a favor that becomes negated with a spell you already have? Isn't that redundant? For example, if you go swift anklet on cat, you can help an ally on one side, recap the xp flag, run to the far side, drop level 2 ice storm and get creep xp/gold, then run back or do whatever you want. Plus the character is squishy, you want to be fast so you can run around, locking stuff, blasting creep waves, be out of range of a fast melee dg. Heavens wrath 250 dmg won't save you against a beast with wand of speed or swift anklet of their own. Once you're caught, you're finished.
Not to mention I played a game as random, got sedna, took cloak of night favor item, and everytime enemy team would snipe, they follow up with double wrath. So after snipe, I use cloak to jump - both wraths miss, everytime, all game long..... useless favor. I like it on TB on leviathan, or reg on exile, that's about it really. Much better options out there, and you can't really deny that.