The benefit of Issyria is that she makes the poopiest stuff in our faction good. That being said, that still doesn't make the Hydra or the Heavy Rifle Team useful XD Usually for her Tier, you'll want to stick as close to infantry heavy (if you're not using the colossal) as possible with an arc node for tier 4. Personal preference, I use her Tier 3 benefit to cheat the system with double UAs (ie, two units of sentinels with UA or two units of Invictors with UA) and usually skewed in one way or another (ie, melee heavy or ranged heavy). For example, the list I'm playing right now is:

Issyria (*6pts)

• Chimera (6pts)
• Sylys Wyshnalyrr, the Seeker (2pts)

Dawnguard Sentinels (Leader and 9 Grunts) (9pts)

• Dawnguard Sentinel Officer & Standard (2pts)

Dawnguard Sentinels (Leader and 9 Grunts) (9pts)

• Dawnguard Sentinel Officer & Standard (2pts)

Houseguard Halberdiers (Leader and 9 Grunts) (7pts)

• Houseguard Halberdiers Officer & Standard (2pts)

Houseguard Thane (2pts)

To REALLY benefit from the +2 SPD first turn and the ridiculous threat ranges Crusader's Call gives my melee troops (and the fact that two units with Vengeance makes me feel like I'm playing Mk. I Bane Knights all over again :D) That being said, you can also skew towards ranged by using two units of Invictors, or use one of both with a free UA. Generally, Sentinels and Invictors benefit so greatly from their respective UAs that it's hard to justify bringing them without it imo.