Activate Wandering Fumarole's ability so that it becomes a creature.
Activate it to switch its power and toughness infinite times to get infinite Ceaseless Searblades triggers.
Repeat.

Infinitely powerful creature until end of turn

Ceaseless Searblades

Wandering Fumarole

Activate Lavaclaw Reaches's last ability by paying {1}{B}{R}, causing it to become a 2/2 Elemental creature with a new ability until end of turn.
Activate that new ability by paying {0}.
Ceaseless Searblades triggers, getting +1/+0 until end of turn.
Resolve Lavaclaw Reaches's ability, having no effect.
Repeat from step 2.

Combos with "Ceaseless Searblades"