Boldtusk and Sabina work well together because Boldtusk is tankier and his attack buff increases Sabina’s board damage. Sabina’s high attack stat increases purple board damage especially with Gambler’s Stance active. Melendor, below, is a green clone of Sabina. See Wu Kong team link below for more discussion of Boldtusk, Sabina, and Melendor.
Sonya has a higher defense and HP than Caedmon, the other Piercing Strike. Works well with Melendor versus blue bosses/ double blue defense teams and Sabina versus yellow bosses/ double yellow defense teams and either versus most other situations except green bosses/ double green defense teams.
Li Xiu and Skittleskull can work well with a defense team that plays to their strengths. Because they are attack all drain mana and attack all attack debuff, you don’t have to worry about the defense team A.I. picking the wrong attacking hero to zap. Also the trickle of mana that defense teams get helps charge their special faster.
Many of my alliance fellow resist leveling Wu Kong, his special works best with a team build around it, but he increases board combos/ cascades by x1.938 damage. see Wu Kong team discussion
Melendor is a green clone of Sabina, see above, and really compliments her by giving your roster more flexibility. Plus his stats and healing go well with Wu Kong, see above link. While Elkanen is more of a green tank.
Personally I have one max Grimm, almost done leveling a 8/8 Kiril, and I am feeding all my 1* blue heroes to a second Grimm to get his special to 8/8 using only farmable ascension materials.
Using only farmable ascension materials, 4* heroes are the strongest, so they are good to add flexibility to your teams and in war were heroes can be used only once.
My alliance fellow has two Rigards and I am so jealous. Rigard is not only a very tanky healer, but heal all and cleanse all. Vivica is the only other heal all and cleanse all and she is slow mana instead of average. First Rigard is great for most 4* defense teams in raid or war. Second Rigard is great versus war defense teams especially because of Rigard’s help against the revenge bar.
Among the Ramming Pulverizer heroes, Tiburtus tends to be third in line after Grimm ( strong against red, weak against green, highest attack, lowest defense of Ramming Pulverizer ) and Gormek ( weak against blue, strong against green, lowest attack, highest defense of Ramming Pulverizer ) which compliment each other. But Tiburtus is weak against purple where Wu Kong and Delilah’s yellow minions can help ( yes they are strong versus purple, but 15 yellow minions are usually too distracting during the 90 seconds of terror known as a titan timer )
Squire Wabbit has the highest 3* red attack stat and can be maxed using only farmable ascension items. Useful for challenge events and to fill out your second half war teams.