Riot, Leblanc doesn't have a predictable pattern.

And that's actually why she's not that deceptive. In order for Leblanc to deceive her opponents, her opponents need to expect something from her. If she can just dash in, throw a chain and burst someone down she's not that deceptive. She's just a fast burst mage. Arguably, a lot of players enjoyed playing that Leblanc (pre-rework Leblanc) precisely because she was quick and agile. With a delay, she loses her "fun to play" factor while also not being that deceptive.

If you want Leblanc to be deceptive, give players the tools necessary. For example, even with minimal changes, you can make Sigil of Malice more deceptive by shfiting some of its power around.

Instead of always dealing a ton of damage, make it deal RIDICULOUS amounts of damage, but only at random intervals. For example,

Heart of the Rose (Passive)

Part 1: Leblanc's spells mark her targets with Sigil of Malice after a delay. Her other damaging spells consume the mark to deal bonus magic damage equal to 60% of her ability power (no flat damage bonus).

Part 2: Every 60 to 240 seconds (randomly determined initially but visible to Leblanc as a fixed value once determined), Leblanc gains the buff Heart of the Rose for 20 seconds (which visibly surrounds her as well as any clones that are active when it's active with a glowing aura). While Leblanc has the Heart of the Rose, Sigil of Malice deals 5% additional damage for every 1% of her missing health. When Leblanc kills an enemy champion, Heart of the Rose's "cooldown" (the 60 to 240 seconds recharge time that's randomly determined) is reduced.

What this does is take away from Leblanc's perpetual burst power in favor of a timed but UNMATCHED burst power. Since Heart of the Rose activates randomly, her opponents will not be able to determine for sure (but will have some idea) of when Leblanc's Heart of the Rose is active. Meanwhile, Leblanc can poke in and out with Distortion to lower her opponents (and her own) health slightly if she knows Heart of the Rose will activate in, let's say, 20 seconds. She's still strong when she doesn't have Heart of the Rose (60% ability power scaling compared to flat + 80% on live) but becomes potentially pentakill potential strong when she does have it, instilling fear into the hearts of her enemies (if played properly) because they don't know precisely when Leblanc's Heart of the Rose buff might activate. At the same time, Leblanc also has to be somewhat low on health for the OMG BROKEN burst power to activate even with Heart of the Rose on so it's not like she can't get burst down back in return. And just like that, Leblanc would have plenty of room for deception and bluffs using even her predictable RR clone because her enemies would be forced to run from it (or call her bluff and risk getting instaburst).

In other words, Leblanc needs to be visibly threatening at certain time intervals with indicators that enemies can learn to recognize and understand. Without these, she has no room for actual deception because deception plays on the perceptions of her opponents. Opponents that are completely unaware or unable to react are unable to be deceived.