Just leveled up a Yareli, after feeding the first one to the Helminth to keep my only spare slot open. Seems like good potential for fun here.
Kompressa - I love this gun. Whoever came up with this gun\s behavior? Good job, you. It's not the be-all endgame super pistol, but it's fun and I find it pretty effective. "Carpet bomb with explosive bubbles that spread viral and other statuses very nicely" ? Sold. "Sticks to nulli bubbles and wrecks them" ? Extra Sold. Has some weird behavior if you try to do punchthrough and Mag or Void status shenanigans though. Good mix with Aquablades, feels more "signature" than some others.
Yareli - mixed feelings here. Lots of interesting gameplay hooks that never quite come to fruition. I don't think she'll ever be a strong Steel Path contender, but she has the potential for lots of fun running about. I like having fun, so generally a thumbs up.
Passive - not doing much for me. I like the attachment to mobility for a mobile frame, but pistol crit chance is only really useful in a few cases (extremely high chance/multi stat or the 200 pushes it into guaranteed crits). Actually feels like you're trying to encourage continued Kuva Nukoring there. Especially a miss with the dismal crit stats on her signature sidearm. Given that the Kompressa and Aquablades feels like a minor theme of status effects, maybe a DoT or plain pistol damage bonus (coded in the "faction hate" mod channel so it double dips on status damage) would feel more appropriate. Possibly ramp up with speed, or multiplied (if the DoT boost, for aquablades) when boosting on Merulina so you can dash through a crowd and leave some serious unhappiness behind, also since you can't attack while boosting.
Sea Snares - Solid CC skill, does what it needs to do and does it pretty well. The VFX looks like the Lifted status effect, and I wish this (along with things like Well Of Life and Spellbind) actually counted as such. Would open up some currently hard to use combos, notably the Saxum set. Still a very good skill, and easily her best when looked at in a vacuum. Merulina - Needs to be moddable. Period. We have a pile of interesting combat effects available for K Drives that aren't very useful because enemy density is too low in the open worlds. We finally have a hoverboard in a target rich environment, and nothing. Thrash Landing builds could be a thing, Juice offers an interesting way to regain energy, etc.
More problematic from a balance perspective, having the player mounted on Merulina counting as airborne could allow extra toughness from Aerodynamic / Aviator and maybe interesting interactions with Pax Soar or the Motus set.
Aquablades - not really enough strength to carry a full build on its back, I'm treating this as more of a supplemental skill. Really interesting in a few cases as a Helminth infusion, particularly Limbo and Rhino. No strong opinion yet, just a wait and see while fiddling with it. Riptide - Feels like Airburst and old enemy distributing Tornado had a slightly disappointing baby. Semi-effective as a gathering skill, the tweaked spray isn't that bad from my perspective. Tighter grouping is always appreciated, but I can work with this, and the somewhat wide attract radius helps (wouldn't mind a 12 meter one to match Nidus, tho). It would be nice to have a very short (1-2 sec) but moddable duration, however, rather than the current one touchable by only Natural Casting. With the continuous pull behavior, both very short (stagger and clump) and very long (tight group to aim this envoy at) durations could have uses. Add in a strength scaling pull force and it's tweakable enough to find use. If I come up with a good aquablades setup, this is likely to be replaced by Airburst as it will probably be more useful for gathering targets at the right height.
Overall a good runup, but you remember that time Otto beefed the landing?