Okay, so there are a number of options to making
Worldslayer work but perhaps the best would be to have creatures that either produce new creatures when they die, i.e.,
Thragtusk or
Doomed Traveler, or indestructible creatures (or at least effects that could make them as such for a turn.
So based on your decklist, you're far too fragmented for it to be effective. With so many one and two offs, you're seldom going to see the sort of consistency you want to be anything close to competitive. You really need to focus and hone in more on the specific combo(s) you're wanting to run.
What are some of the pieces that you could run with
Worldslayer that would work? With white in the mix you could use
Rootborn Defenses or
Faith's Reward to either make your stuff indestructible or otherwise return to play after a 'slayer wipe. In a similar vein,
Gideon, Champion of Justice would serve the role of 'slayer just fine, as his zero ability makes him indestructible, you swing, wipe the board, and smile as he and
Worldslayer are the only things left on the field. You could also make use of things like
Oblivion Ring,
Fiend Hunter, and
Journey to Nowhere to exile your stuff, wipe the field, and then you get your pieces back. Again, the key is to wipe everything out while maintaining some advantage on your side.
Blue adds a fair number of options, including the potential for unblockable creatures. However, you're certainly asking a lot to have an unblockable, indestructible creature. I mean 4x
Invisible Stalker, paired with 4x
Darksteel Plate certainly wouldn't be a bad option. Personally, I would suggest adding green to the mix as it would give you the added ramp you need to get 'slayer out faster (and it also makes some of the other indestructible pieces more accessible). Specifically, you would be able to toss in
Predator Ooze which, paired with 'slayer would essentially be GG for the opponent. But otherwise you would be able to toss in others like
Stuffy Doll,
Creepy Doll or
Darksteel Myr. Alternately, if you went black instead of green,
Phylactery Lich would work just as well.
Okay, so I've just gone through some options on where you COULD go with it. Now about the current build.
- I really just don't see where you're going to set off
Worldslayer in even a remotely consistent fashion, much less one where you actually benefit from it. None of your creatures are all that imposing and the only spell that would make it a one-sided affair requires you to have less than 5 life (it's typically not a good strategy to try to get your ass handed to you before you do something useful).
- Your spells don't show a clear line of reasoning. For instance, you have counters in
Mana Leak and
Stoic Rebuttal... but none other than those 3 spells. You have combat tricks, but not consistently offensive or defensive ones (nor do they give you any abilities consistently). 'Slayer needs to connect with the opponent, yet you have no unblockables, no flying, and only one
Artful Dodge? Also, why so much emphasis on artifacts, many of which don't really help your goal?
I realize that this might come off as harsh, but really, the deck needs some more focus and direction. Make it a clearer commitment to a combo and you should be good to go. Now, that being said, don't put all your eggs in one basket, as you need ways to win without the 'slayer going off. Don't forget to consider those when making your changes.
I hope some of this helps.
Good luck!